# ⓘ 115 (number)

## ⓘ 115 (number)

115 has a square sum of divisors:

σ 115 = 1 + 5 + 23 + 115 = 144 = 12 2. {\displaystyle \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 × 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 ⋅ 2 115 − 1 = 4 776 913 109 852 041 418 248 056 622 882 488 319, {\displaystyle 115\cdot 2^{115}-1=4\;776\;913\;109\;852\;041\;418\;248\;056\;622\;882\;488\;319,}

is a prime number.