261 (two hundred
ndsixty-one) is a natural number proceeded by the number
260
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Year 260 ( CCLX) was a leap year starting on Sunday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Saecularis and Donatus (or, less frequently, year 1013 ''Ab ...
and followed by
262
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Year 262 (Roman numerals, CCLXII) was a common year starting on Wednesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Gallienus and Faustianus (or, less fre ...
. It has the prime factorization 3
2·29.
Mathematical properties
There are six divisors of this number, the divisors being , , , , , and 261 itself. 261 is a
deficient number, since
261 is
nonagonal number,
unique period in
base 2, and the number of possible unfolded
tesseract patterns.
261 is a
lucky number, as well as an
odious number, meaning it has an odd number of 1's in its
binary expansion, which is (with 3 ones in it).
In other fields
*
261
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Year 261 ( CCLXI) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Gallienus and Taurus (or, less frequently, year 1014 ''A ...
AD, a calendar year
*
261 AM No official radio stations broadcast on AM frequency 261 kHz:
Inactive
*Germany: Formerly Radio Wolga and Radioropa Info
Radioropa Info was the name of various German-language privately owned longwave radio stations. They were mainly a ...
, a radio frequency
*
261 BC
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Year 261 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Flaccus and Crassus (or, less frequently, year 493 ''Ab urbe condita''). The denomination 261 BC for this year has been ...
, a calendar year
* 261 Fearless, a non-profit organization started by
Kathrine Switzer, who in 1967 wore
bib number
In many sports, a competition number is used to identify and differentiate the competitors taking part in a competitive endeavour. For example, runners in a race may wear prominent competition numbers so that they may be clearly identified from a ...
261 when she became the first woman to run the
Boston Marathon
The Boston Marathon is an annual marathon race hosted by several cities and towns in greater Boston in eastern Massachusetts, United States. It is traditionally held on Patriots' Day, the third Monday of April. Begun in 1897, the event was i ...
as a numbered entrant
* +261, a
country calling code
Country calling codes or country dial-in codes are telephone number prefixes for reaching telephone subscribers in the networks of the member countries or regions of the International Telecommunication Union (ITU). The codes are defined by the ...
; see
telephone numbers in Madagascar
*
H.261, a video compression standard
Military / Transportation
*
Flight 261, several airliner incidents
*
German submarine U-261
German submarine ''U-261'' was a Type VIIC U-boat of Nazi Germany's ''Kriegsmarine'' during World War II. The submarine was laid down on 17 May 1941 at the Bremer Vulkan yard at Bremen-Vegesack as yard number 26, launched on 16 February 1942 an ...
, which was sunk in 1942
*
KiHa 261 series, a type of diesel train in Japan
*
Messerschmitt Me 261, an airplane of the late 1930s
*
Milwaukee Road 261, a restored steam locomotive built in 1944
*
No. 261 Squadron RAF
No. 261 Squadron RAF was a squadron of the Royal Air Force during World War I and World War II. It was involved in the defence of Malta from August 1940 till May 1941 and the Burma Campaign, campaign in Burma.
History
Formation and World War I ...
, of World War I and World War II
*
VMM-261, a United States Marine Corps squadron
;Space
*
261 Prymno
Prymno (minor planet designation: 261 Prymno) is a somewhat large Main belt asteroid. It is classified as a B-type asteroid and probably has a primitive composition not unlike common C-type carbonaceous asteroids.
It was discovered by C. H. F. ...
, a minor planet
*
Kosmos 261
Kosmos 261 (russian: Космос 261 meaning ''Cosmos 261''), also known as DS-U2-GK No.1, was a Soviet satellite which was launched in 1968 as part of the Dnepropetrovsk Sputnik programme. It was a spacecraft, which was built by the Yuzhnoye Des ...
, a Soviet satellite launched in 1968
*
NGC 261
NGC 261 is a diffuse nebula
A nebula ('cloud' or 'fog' in Latin; pl. nebulae, nebulæ or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral or molecular hydrogen and also cosmic dust. Nebu ...
, a diffuse nebula located in the constellation Tucana
;See also
*
List of highways numbered 261
*
References
{{Integers, 2
Integers