81307155 has 32 divisors (see below), whose sum is σ = 135201600. Its totient is φ = 41674752.

The previous prime is 81307147. The next prime is 81307157. The reversal of 81307155 is 55170318.

It is not a de Polignac number, because 81307155 - 2³ = 81307147 is a prime.

It is a super-2 number, since 2×81307155² = 13221706908388050, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81307157) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 177687 + ... + 178143.

It is an arithmetic number, because the mean of its divisors is an integer number (4225050).

Almost surely, 2^81307155 is an apocalyptic number.

81307155 is a deficient number, since it is larger than the sum of its proper divisors (53894445).

81307155 is a wasteful number, since it uses less digits than its factorization.

81307155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 903.

The product of its (nonzero) digits is 4200, while the sum is 30.

The square root of 81307155 is about 9017.0480202780. The cubic root of 81307155 is about 433.2210876272.

The spelling of 81307155 in words is "eighty-one million, three hundred seven thousand, one hundred fifty-five".