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

In mathematics

115 has a square sum of divisors:

:<math>\sigma(115)=1+5+23+115=144=12^2.</math>

There are 115 different rooted trees with exactly eight nodes, 115 inequivalent ways of placing six rooks on a 6&nbsp;&times;&nbsp;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 rectangular stamps.

115 is also a heptagonal pyramidal number. The 115th Woodall number,

:<math>115\cdot 2^{115}-1=4\;776\;913\;109\;852\;041\;418\;248\;056\;622\;882\;488\;319,</math>

is a prime number.

115 is the sum of the first five heptagonal numbers.

See also

  • 115 (disambiguation)

References