81307137 has 16 divisors (see below), whose sum is σ = 114632000. Its totient is φ = 51119424.

The previous prime is 81307129. The next prime is 81307147. The reversal of 81307137 is 73170318.

It is not a de Polignac number, because 81307137 - 2³ = 81307129 is a prime.

It is a super-2 number, since 2×81307137² = 13221701054273538, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81307147) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9939 + ... + 16167.

It is an arithmetic number, because the mean of its divisors is an integer number (7164500).

Almost surely, 2^81307137 is an apocalyptic number.

It is an amenable number.

81307137 is a deficient number, since it is larger than the sum of its proper divisors (33324863).

81307137 is a wasteful number, since it uses less digits than its factorization.

81307137 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6480.

The product of its (nonzero) digits is 3528, while the sum is 30.

The square root of 81307137 is about 9017.0470221686. The cubic root of 81307137 is about 433.2210556580.

The spelling of 81307137 in words is "eighty-one million, three hundred seven thousand, one hundred thirty-seven".