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360 (number)
360 (three hundred sixty) is the natural number following 359 and preceding 361. In mathematics *The divisors of 360 are 1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 18, 20, 24, 30, 36, 40, 45, 60, 72, 90, 120, 180 and 360, making a total of 24 divisors. *360 is a highly composite number. Not only is 360 highly composite, but it is also one of only 7 numbers such that no number less than twice as much has more divisors; the others are 1, 2, 6, 12, 60, and 2520. . 360 is also a superior highly composite number, a colossally abundant number, a refactorable number and a 5-smooth number. *360 is the smallest number divisible by every natural number from 1 to 10 except 7. *One of 360's divisors is 72, which is the number of primes below it. *The sum of Euler's totient function In number theory, Euler's totient function counts the positive integers up to a given integer that are relatively prime to . It is written using the Greek letter phi as \varphi(n) or \phi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 numbers'', and numbers used for ordering are called '' ordinal numbers''. Natural numbers are sometimes used as labels, known as '' nominal numbers'', having none of the properties of numbers in a mathematical sense (e.g. sports jersey numbers). Some definitions, including the standard ISO 80000-2, begin the natural numbers with , corresponding to the non-negative integers , whereas others start with , corresponding to the positive integers Texts that exclude zero from the natural numbers sometimes refer to the natural numbers together with zero as the whole numbers, while in other writings, that term is used instead for the integers (including negative integers). The natural numbers form a set. Many other number sets are built by suc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
24 (number)
24 (twenty-four) is the natural number following 23 and preceding 25. The SI prefix for 1024 is yotta (Y), and for 10−24 (i.e., the reciprocal of 1024) yocto (y). These numbers are the largest and smallest number to receive an SI prefix to date. In mathematics 24 is an even composite number, with 2 and 3 as its distinct prime factors. It is the first number of the form 2''q'', where ''q'' is an odd prime. It is the smallest number with exactly eight positive divisors: 1, 2, 3, 4, 6, 8, 12, and 24; thus, it is a highly composite number, having more divisors than any smaller number. Furthermore, it is an abundant number, since the sum of its proper divisors ( 36) is greater than itself, as well as a superabundant number. In number theory and algebra *24 is the smallest 5- hemiperfect number, as it has a half-integer abundancy index: *:1 + 2 + 3 + 4 + 6 + 8 + 12 + 24 = 60 = × 24 *24 is a semiperfect number, since adding up all the proper divisors ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colossally Abundant Number
In mathematics, a colossally abundant number (sometimes abbreviated as CA) is a natural number that, in a particular, rigorous sense, has many divisors. Formally, a number ''n'' is said to be colossally abundant if there is an ε > 0 such that for all ''k'' > 1, :\frac\geq\frac where ''σ'' denotes the sum-of-divisors function. All colossally abundant numbers are also superabundant numbers, but the converse is not true. The first 15 colossally abundant numbers, 2, 6, 12, 60, 120, 360, 2520, 5040, 55440, 720720, 1441440, 4324320, 21621600, 367567200, 6983776800 are also the first 15 superior highly composite numbers, but neither set is a subset of the other. History Colossally abundant numbers were first studied by Ramanujan and his findings were intended to be included in his 1915 paper on highly composite numbers. Unfortunately, the publisher of the journal to which Ramanujan submitted his work, the London Mathematical Society, was in fina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superior Highly Composite Number
In mathematics, a superior highly composite number is a natural number which has the highest ratio of its number of divisors to ''some'' positive power of itself than any other number. It is a stronger restriction than that of a highly composite number, which is defined as having more divisors than any smaller positive integer. The first 10 superior highly composite numbers and their factorization are listed. For a superior highly composite number ''n'' there exists a positive real number ''ε'' such that for all natural numbers ''k'' smaller than ''n'' we have :\frac\geq\frac and for all natural numbers ''k'' larger than ''n'' we have :\frac>\frac where ''d(n)'', the divisor function, denotes the number of divisors of ''n''. The term was coined by Ramanujan (1915). For example, the number with the most divisors per square root of the number itself is 12; this can be demonstrated using some highly composites near 12. \frac\approx 1.414, \frac=1.5, \frac\approx 1.633, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2520 (number)
2520 (two thousand five hundred twenty) is the natural number following 2519 and preceding 2521. In mathematics 2520 is: *the smallest number divisible by all integers from 1 to 10, i.e., it is their least common multiple. *half of 7! ( 5040), meaning 7 factorial, or 1×2×3×4×5×6×7. *the product of five consecutive numbers, namely 3×4×5×6×7. *a superior highly composite number. *a colossally abundant number. *the last highly composite number which is half of the next highly composite number. *the last highly composite number that is a divisor of all following highly composite numbers. *palindromic in bases 11 (199111), and a repdigit in bases 55, 59 and 62. *a Harshad number in bases 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 and 16. *the aliquot sum of 1080. *part of the 53-aliquot tree. The complete aliquot sequence starting at 1080 is: 1080, 2520, 6840, 16560, 41472, 82311, 27441, 12209, 451, 53, 1, 0. Factors The factors, also called divisor In mathemat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Highly Composite Number
__FORCETOC__ A highly composite number is a positive integer with more divisors than any smaller positive integer has. The related concept of largely composite number refers to a positive integer which has at least as many divisors as any smaller positive integer. The name can be somewhat misleading, as the first two highly composite numbers (1 and 2) are not actually composite numbers; however, all further terms are. The late mathematician Jean-Pierre Kahane has suggested that Plato must have known about highly composite numbers as he deliberately chose 5040 as the ideal number of citizens in a city as 5040 has more divisors than any numbers less than it. Ramanujan wrote and titled his paper on the subject in 1915. Examples The initial or smallest 38 highly composite numbers are listed in the table below . The number of divisors is given in the column labeled ''d''(''n''). Asterisks indicate superior highly composite numbers. The divisors of the first 15 highly composite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
180 (number)
180 (one hundred ndeighty) is the natural number following 179 and preceding 181. In mathematics 180 is an abundant number, with its proper divisors summing up to 366. 180 is also a highly composite number, a positive integer with more divisors than any smaller positive integer. One of the consequences of 180 having so many divisors is that it is a practical number, meaning that any positive number smaller than 180 that is not a divisor of 180 can be expressed as the sum of some of 180's divisors. 180 is a Harshad number and a refactorable number. 180 is the sum of two square numbers: 122 + 62. It can be expressed as either the sum of six consecutive prime numbers: 19 + 23 + 29 + 31 + 37 + 41, or the sum of eight consecutive prime numbers: 11 + 13 + 17 + 19 + 23 + 29 + 31 + 37. 180 is an Ulam number, which can be expressed as a sum of earlier terms in the Ulam sequence only as 177 + 3. 180 is a 61- gonal number. Half a circle has 180 degrees, and thus a U-turn i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
120 (number)
120, read as one hundred ndtwenty, is the natural number following 119 and preceding 121. In the Germanic languages, the number 120 was also formerly known as "one hundred". This "hundred" of six score is now obsolete, but is described as the long hundred or great hundred in historical contexts. In mathematics 120 is * the factorial of 5 i.e. 5 × 4 × 3 × 2 × 1 * the fifteenth triangular number, as well as the sum of the first eight triangular numbers, making it also a tetrahedral number. 120 is the smallest number to appear six times in Pascal's triangle (as all triangular and tetragonal numbers appear in it). Because 15 is also triangular, 120 is a doubly triangular number. 120 is divisible by the first 5 triangular numbers and the first 4 tetrahedral numbers. It is the eighth hexagonal number. * highly composite, superior highly composite, superabundant, and colossally abundant number, with its 16 divisors being more than any number lower than it has, and it is al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
90 (number)
90 (ninety) is the natural number preceded by 89 and followed by 91. In the English language, the numbers 90 and 19 are often confused, as they sound very similar. When carefully enunciated, they differ in which syllable is stressed: 19 /naɪnˈtiːn/ vs 90 /ˈnaɪnti/. However, in dates such as 1999, and when contrasting numbers in the teens and when counting, such as 17, 18, 19, the stress shifts to the first syllable: 19 /ˈnaɪntiːn/. In mathematics 90 is a pronic number, as it is the product of 9 and 10. It is nontotient, and divisible by the sum of its base 10 digits, which makes it a Harshad number. *It is the third unitary perfect number, since it is the sum of its unitary divisors excluding itself, and because it is equal to the sum of a subset of its divisors, it is also a semiperfect number. *90 is a Stirling number of the second kind S(n,k) from a n of 6 and a k of 3, as it is the number of ways of dividing a set of six objects into three non empty subsets. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
72 (number)
72 (seventy-two) is the natural number following 71 and preceding 73. It is half a gross or 6 dozen (i.e., 60 in duodecimal). In mathematics Seventy-two is a pronic number, as it is the product of 8 and 9. 72 is an abundant number, with a total of 12 factors, and a Euler totient of 24. 72 is also a highly totient number, as there are 17 solutions to the equation φ(''x'') = 72, more than any integer below 72. It is equal to the sum the sum of its preceding smaller highly totient numbers 24 and 48, and contains the first six highly totient numbers 1, 2, 4, 8, 12 and 24 as a subset of its proper divisors. 144, or twice 72, is also highly totient, as is 576, the square of 24. While 17 different integers have a totient value of 72, the sum of Euler's totient function φ(''x'') over the first 15 integers is 72. 72 is also a Harshad number in decimal, as it is divisible by the sum of its digits. *72 is the smallest Achilles number, as it's a powerful number that is not itself a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
60 (number)
60 (sixty) () is the natural number following 59 and preceding 61. Being three times 20, it is called '' threescore'' in older literature ('' kopa'' in Slavic, ''Schock'' in Germanic). In mathematics * 60 is a highly composite number. Because it is the sum of its unitary divisors (excluding itself), it is a unitary perfect number, and it is an abundant number with an abundance of 48. Being ten times a perfect number, it is a semiperfect number. * It is the smallest number divisible by the numbers 1 to 6: there is no smaller number divisible by the numbers 1 to 5. * It is the smallest number with exactly 12 divisors. * It is one of seven integers that have more divisors than any number less than twice itself , one of six that are also lowest common multiple of a consecutive set of integers from 1, and one of six that are divisors of every highly composite number higher than itself. * It is the smallest number that is the sum of two odd primes in six ways.Wells, D. '' The Pengu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
45 (number)
45 (forty-five) is the natural number following 44 and followed by 46. In mathematics Forty-five is the smallest odd number that has more divisors than n+1, and that has a larger sum of divisors than n+1. It is the sixth positive integer with a prime factorization of the form p^q, with and being prime. Forty-five is the sum of all single-digit decimal digits: 0+1+2+3+4+5+6+7+8+9=45. It is, equivalently, the ninth triangle number. Forty-five is also the fourth hexagonal number and the second hexadecagonal number, or 16-gonal number. It is also the second smallest triangle number (after 1 and 10) that can be written as the sum of two squares. Since the greatest prime factor of 45^+1=2026 is 1,013, which is much more than 45 twice, 45 is a Størmer number. In decimal, 45 is a Kaprekar number and a Harshad number. Forty-five is a little Schroeder number; the next such number is 197, which is the 45th prime number. Forty-five is conjectured from Ramsey n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
