115 (number)

115 (one hundred [and] fifteen) is the natural number following 114 and preceding 116.

In mathematics
115 has a square sum of divisors:
 * $$\sigma(115)=1+5+23+115=144=12^2.$$

There are 115 different rooted trees with exactly eight nodes, 115 inequivalent ways of placing six rooks on a 6 &times; 6 chess board in such a way that no two of the rooks attack each other, and 115 solutions to the stamp folding problem for a strip of seven stamps.

115 is also a heptagonal pyramidal number. The 115th Woodall number,
 * $$115\cdot 2^{115}-1=4\;776\;913\;109\;852\;041\;418\;248\;056\;622\;882\;488\;319,$$

is a prime number. 115 is the sum of the first five heptagonal numbers.