181 (one hundred ndeighty-one) is the

natural number In mathematics, the natural numbers are those numbers used for counting (as in "there are ''six'' coins on the table") and ordering (as in "this is the ''third'' largest city in the country"). Numbers used for counting are called ''cardinal ...

following 180 and preceding

182 Year 182 ( CLXXXII) was a common year starting on Monday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Sura and Rufus (or, less frequently, year 935 ''Ab urbe condita'') ...

In mathematics

* 181 is an odd number * 181 is a

centered number The centered polygonal numbers are a class of series of figurate numbers, each formed by a central dot, surrounded by polygonal layers of dots with a constant number of sides. Each side of a polygonal layer contains one more dot than each side i ...

** 181 is a

centered pentagonal number A centered pentagonal number is a centered figurate number that represents a pentagon with a dot in the center and all other dots surrounding the center in successive pentagonal layers. The centered pentagonal number for ''n'' is given by th ...

** 181 is a centered 12-gonal number ** 181 is a centered 18-gonal number ** 181 is a centered 30-gonal number ** 181 is a

centered square number In elementary number theory, a centered square number is a centered figurate number that gives the number of dots in a square with a dot in the center and all other dots surrounding the center dot in successive square layers. That is, each cen ...

** 181 is a

star number A star number is a centered figurate number, a centered hexagram (six-pointed star), such as the Star of David, or the board Chinese checkers is played on. The ''n''th star number is given by the formula ''Sn'' = 6''n''(''n'' − 1) + 1. The ...

that represents a centered hexagram (as in the game of Chinese checkers) * 181 is a

deficient number In number theory, a deficient number or defective number is a number ''n'' for which the sum of divisors of ''n'' is less than 2''n''. Equivalently, it is a number for which the sum of proper divisors (or aliquot sum) is less than ''n''. For ex ...

, as 1 is less than 181 * 181 is an odious number * 181 is a

prime number A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only ways ...

** 181 is a

Chen prime A prime number ''p'' is called a Chen prime if ''p'' + 2 is either a prime or a product of two primes (also called a semiprime). The even number 2''p'' + 2 therefore satisfies Chen's theorem. The Chen primes are named after Chen Jingru ...

** 181 is a dihedral prime ** 181 is a full reptend prime ** 181 is a palindromic prime ** 181 is a strobogrammatic prime, the same when viewed upside down ** 181 is a

twin prime A twin prime is a prime number that is either 2 less or 2 more than another prime number—for example, either member of the twin prime pair (41, 43). In other words, a twin prime is a prime that has a prime gap of two. Sometimes the term ''twin p ...

with 179 * 181 is a

square-free number In mathematics, a square-free integer (or squarefree integer) is an integer which is divisible by no square number other than 1. That is, its prime factorization has exactly one factor for each prime that appears in it. For example, is square-fr ...

* 181 is an undulating number, if written in the ternary, the negaternary, or the

nonary A ternary numeral system (also called base 3 or trinary) has three as its base. Analogous to a bit, a ternary digit is a trit (trinary digit). One trit is equivalent to log2 3 (about 1.58496) bits of information. Although ''ternary'' m ...

numeral system A numeral system (or system of numeration) is a writing system for expressing numbers; that is, a mathematical notation for representing numbers of a given set, using digits or other symbols in a consistent manner. The same sequence of symbo ...

s * 181 is the difference of 2

square number In mathematics, a square number or perfect square is an integer that is the square of an integer; in other words, it is the product of some integer with itself. For example, 9 is a square number, since it equals and can be written as . The usu ...

s: 91² – 90² * 181 is the sum of 2 consecutive

s: 9² + 10² * 181 is the sum of 5 consecutive

s: 29 + 31 + 37 + 41 + 43

In geography

* Langenburg No. 181, Saskatchewan rural municipality in

Saskatchewan, Canada Saskatchewan ( ; ) is a province in western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on the south by the U.S. states of Montana and North Dak ...

181 Fremont Street 181 Fremont is an mixed-use skyscraper in the South of Market (San Francisco), South of Market District of San Francisco, California. The building, designed by Heller Manus Architects, is located adjacent to the San Francisco Transbay developmen ...

proposed skyscraper in San Francisco, California * 181 West Madison Street, Chicago

In the military

* 181st (Brandon) Battalion, CEF was a unit in the Canadian Expeditionary Force during World War I * 181st Airlift Squadron is a unit of the

Texas Air National Guard The Texas Air National Guard (TX ANG) is the aerial militia of the State of Texas, United States of America. It is, along with the Texas Army National Guard, an element of the Texas National Guard. No element of the Texas Air National Guard is ...

* 181st Infantry Brigade of the

United States Army The United States Army (USA) is the land warfare, land military branch, service branch of the United States Armed Forces. It is one of the eight Uniformed services of the United States, U.S. uniformed services, and is designated as the Army o ...

based at

Fort McCoy, Wisconsin Fort McCoy is a United States Army installation on between Sparta and Tomah, Wisconsin, in Monroe County. In 1909, there were two separate camps named Camp Emory Upton and Camp Robinson; in 1926, these camps were joined together to form Camp ...

* 181st Intelligence Wing is a unit of the

United States Air Force The United States Air Force (USAF) is the Aerial warfare, air military branch, service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part ...

located at Hulman Field, Terre Haute, Indiana * AN/APQ-181 an all-weather, low probability of intercept (LPI)

radar Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, we ...

system for the U.S. Air Force

B-2A Spirit The Northrop (later Northrop Grumman) B-2 Spirit, also known as the Stealth Bomber, is an American heavy strategic bomber, featuring low-observable stealth technology designed to penetrate dense anti-aircraft defenses. A subsonic flying ...

bomber aircraft * Bücker Bü 181 Bestmann single-engine trainer aircraft during World War II * was a ship scheduled to be acquired by the

United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...

, however, the program was cancelled * was a United States Navy

troop transport A troopship (also troop ship or troop transport or trooper) is a ship used to carry soldiers, either in peacetime or wartime. Troopships were often drafted from commercial shipping fleets, and were unable land troops directly on shore, typicall ...

during World War II * was a United States Navy oiler following the

Vietnam War The Vietnam War (also known by other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vietnam a ...

* was a United States Navy ATA-174-class auxiliary ocean

tugboat A tugboat or tug is a marine vessel that manoeuvres other vessels by pushing or pulling them, with direct contact or a tow line. These boats typically tug ships in circumstances where they cannot or should not move under their own power, su ...

during World War II * was a United States Navy ''Alamosa''-class cargo ship following World War II * was a United States Navy following World War I * was a United States Navy ''Porpoise''-class submarine during World War II * was a United States Navy during World War II

In movies

* �
181: Fragments of a Journey in Palestine-Israel
” winner of the 2005

Yamagata International Documentary Film Festival The Yamagata International Documentary Film Festival is a documentary film festival held biennially in Yamagata, Japan ( ). It was first held in October 1989, which makes it one of the longest running documentary film festivals in the world and ...

* The

war film War film is a film genre concerned with warfare, typically about navy, naval, air force, air, or army, land battles, with combat scenes central to the drama. It has been strongly associated with the 20th century. The fateful nature of battle s ...

“ The Enemy Below” revolves around the fictitious , USS ''Hayes'' (DE-181) and a German

U-boat U-boats were naval submarines operated by Germany, particularly in the First and Second World Wars. Although at times they were efficient fleet weapons against enemy naval warships, they were most effectively used in an economic warfare ro ...

In transportation

* The Volkswagen 181 *

Lufthansa Flight 181 Lufthansa Flight 181 was a Boeing 737-230C jetliner (reg. D-ABCE) named the ''Landshut'' that was hijacked on the afternoon of 13 October 1977 by four members of the Popular Front for the Liberation of Palestine, who called themselves Commando ...

, which was hijacked on October 13, 1977 *

London Buses route 181 This is a list of Transport for London (TfL) contracted bus routes in London, England, as well as commercial services that enter the Greater London area (except coaches). Bus services in London are operated by Abellio London, Arriva London, ...

* 181 Union City-New York, a New Jersey Transit bus route from New Jersey to New York * The Córas Iompair Éireann

CIE 181 Class The Córas Iompair Éireann 181 Class locomotives were built in 1966 by General Motors Electro-Motive Division (EMD) and numbered B181 to B192. These locomotives were virtually identical to the earlier 141 Class locomotives, but fitted with ...

diesel locomotives, and numbered B181 to B192, built by General Motors Electro-Motive Division (EMD) in 1966 * East 181st Avenue, a light rail station on the MAX Blue Line in Gresham, Oregon * New York City Subway stations in Manhattan: **

181st Street (IND Eighth Avenue Line) The 181st Street station (also known as 181st Street–Fort Washington Avenue) is a station on the IND Eighth Avenue Line of the New York City Subway. It is located beneath Fort Washington Avenue in the Hudson Heights section of the Washing ...

, at Fort Washington Avenue served by the ** 181st Street (IRT Broadway – Seventh Avenue Line), at St. Nicholas Avenue served by the * 181st Street (Manhattan) * Oregon Route 229, also known as the Siletz Highway No. 181

In other fields

181 is also: * The year AD 181 or 181 BC * The

atomic number The atomic number or nuclear charge number (symbol ''Z'') of a chemical element is the charge number of an atomic nucleus. For ordinary nuclei, this is equal to the proton number (''n''p) or the number of protons found in the nucleus of every ...

of an element temporarily calle
Unoctunium
* 181 Eucharis is a large K-type

Main belt The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, called ...

asteroid *

Minuscule 181 Minuscule 181 (in the Gregory-Aland numbering), α 101 ( Soden), is a Greek minuscule manuscript of the New Testament, on parchment. Palaeographically it has been assigned to the 11th century.K. Aland, M. Welte, B. Köster, K. Junack, "Kurzgefas ...

(in the Gregory-Aland numbering), α 101 ( Soden), is a

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

minuscule Letter case is the distinction between the letters that are in larger uppercase or capitals (or more formally ''majuscule'') and smaller lowercase (or more formally ''minuscule'') in the written representation of certain languages. The writing ...

manuscript A manuscript (abbreviated MS for singular and MSS for plural) was, traditionally, any document written by hand – or, once practical typewriters became available, typewritten – as opposed to mechanically printed or reproduced in ...

of the

New Testament The New Testament grc, Ἡ Καινὴ Διαθήκη, transl. ; la, Novum Testamentum. (NT) is the second division of the Christian biblical canon. It discusses the teachings and person of Jesus, as well as events in first-century Chri ...

* Mir-181 microRNA precursor is a small

non-coding RNA A non-coding RNA (ncRNA) is a functional RNA molecule that is not Translation (genetics), translated into a protein. The DNA sequence from which a functional non-coding RNA is transcribed is often called an RNA gene. Abundant and functionally im ...

molecule *The number of channels on a “ cable-ready” American television set, with 68 over-the-air television channels (12 VHF channels through 13and 56 UHF channels 4 through 69 and 113

cable television Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with bro ...

channels (channel 1 and channels 14 through 125, excluding VHF channels 2 through 13)

References

External links

Number Facts and Trivia: 181

The Number 181

The Positive Integer 181

Number Gossip: 181

181 FM Internet radio
{{DEFAULTSORT:181 (Number) Integers

In mathematics

In geography

In the military

In movies

In transportation

In other fields

See also

References

External links