360 (number)

360 (three hundred [and] sixty) is the natural number following 359 and preceding 361.

• 360 is a highly composite number^[1] and one of only seven numbers such that no number less than twice as much has more divisors; the others are 1, 2, 6, 12, 60, and 2520 (sequence A072938 in the OEIS).

• 360 is also a superior highly composite number, a colossally abundant number, a refactorable number, a 5-smooth number, and a Harshad number in decimal since the sum of its digits (9) is a divisor of 360.

• 360 is divisible by the number of its divisors (24), and it is the smallest number divisible by every natural number from 1 to 10, except 7. Furthermore, one of the divisors of 360 is 72, which is the number of primes below it.

• 360 is the sum of twin primes (179 + 181) and the sum of four consecutive powers of three (9 + 27 + 81 + 243).

• The sum of Euler's totient function φ(x) over the first thirty-four integers is 360.

• 360 is a triangular matchstick number.^[2]

• 360 is the product of the first two unitary perfect numbers:^[3] ${\displaystyle 60\times 6=360.}$

• There are 360 even permutations of 6 elements. They form the alternating group A₆.

A turn is divided into 360 degrees for angular measurement. 360° = 2π rad is also called a round angle. This unit choice divides round angles into equal sectors measured in integer rather than fractional degrees. Many angles commonly appearing in planimetrics have an integer number of degrees. For a simple non-intersecting polygon, the sum of the internal angles of a quadrilateral always equals 360 degrees.

${\displaystyle 361=19^{2},}$ centered triangular number,^[4] centered octagonal number, centered decagonal number,^[5] member of the Mian–Chowla sequence.^[6] There are also 361 positions on a standard 19 × 19 Go board.

${\displaystyle 362=2\times 181=\sigma _{2}(19)}$: sum of squares of divisors of 19,^[7] Mertens function returns 0,^[8] nontotient, noncototient.^[9]

${\displaystyle 364=2^{2}\times 7\times 13}$, tetrahedral number,^[10] sum of twelve consecutive primes (11 + 13 + 17 + 19 + 23 + 29 + 31 + 37 + 41 + 43 + 47 + 53), Mertens function returns 0,^[8] nontotient.

It is a repdigit in bases three (111111), nine (444), twenty-five (EE), twenty-seven (DD), fifty-one (77), and ninety (44); the sum of six consecutive powers of three (1 + 3 + 9 + 27 + 81 + 243); and the twelfth non-zero tetrahedral number.^[11]

365 is the amount of days in a common year. For the common year, see common year.

${\displaystyle 366=2\times 3\times 61,}$ sphenic number,^[12] Mertens function returns 0,^[8] noncototient,^[9] number of complete partitions of 20,^[13] 26-gonal and 123-gonal. There are also 366 days in a leap year.

367 is a prime number, Perrin number,^[14] happy number, prime index prime and a strictly non-palindromic number.

${\displaystyle 368=2^{4}\times 23.}$ It is also a Leyland number.^[15]

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• Wells, D. (1987). The Penguin Dictionary of Curious and Interesting Numbers (p. 152). London: Penguin Group.

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