81518972 has 12 divisors (see below), whose sum is σ = 143116176. Its totient is φ = 40628640.

The previous prime is 81518963. The next prime is 81518977. The reversal of 81518972 is 27981518.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81518977) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 31304 + ... + 33807.

It is an arithmetic number, because the mean of its divisors is an integer number (11926348).

Almost surely, 2^81518972 is an apocalyptic number.

It is an amenable number.

81518972 is a deficient number, since it is larger than the sum of its proper divisors (61597204).

81518972 is a wasteful number, since it uses less digits than its factorization.

81518972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65428 (or 65426 counting only the distinct ones).

The product of its digits is 40320, while the sum is 41.

The square root of 81518972 is about 9028.7857433876. The cubic root of 81518972 is about 433.5969627901.

The spelling of 81518972 in words is "eighty-one million, five hundred eighteen thousand, nine hundred seventy-two".