81316972 has 48 divisors (see below), whose sum is σ = 160876800. Its totient is φ = 35640000.

The previous prime is 81316969. The next prime is 81316993. The reversal of 81316972 is 27961318.

It is a super-2 number, since 2×81316972² = 13224899870497568, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 323847 + ... + 324097.

It is an arithmetic number, because the mean of its divisors is an integer number (3351600).

Almost surely, 2^81316972 is an apocalyptic number.

81316972 is the 7363-rd pentagonal number.

It is an amenable number.

81316972 is a deficient number, since it is larger than the sum of its proper divisors (79559828).

81316972 is a wasteful number, since it uses less digits than its factorization.

81316972 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 502 (or 500 counting only the distinct ones).

The product of its digits is 18144, while the sum is 37.

The square root of 81316972 is about 9017.5923616007. The cubic root of 81316972 is about 433.2385225842.

The spelling of 81316972 in words is "eighty-one million, three hundred sixteen thousand, nine hundred seventy-two".