115 (number)
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115 (one hundred [and] fifteen) is the natural number following 114 and preceding 116.
In mathematics
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 rectangular 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. 115 is the sum of the first five heptagonal numbers.