81312992 has 36 divisors (see below), whose sum is σ = 162325800. Its totient is φ = 40094208.

The previous prime is 81312967. The next prime is 81312997. The reversal of 81312992 is 29921318.

It is a super-2 number, since 2×81312992² = 13223605335984128, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81312997) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 408509 + ... + 408707.

It is an arithmetic number, because the mean of its divisors is an integer number (4509050).

Almost surely, 2^81312992 is an apocalyptic number.

It is an amenable number.

81312992 is a deficient number, since it is larger than the sum of its proper divisors (81012808).

81312992 is a wasteful number, since it uses less digits than its factorization.

81312992 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 435 (or 314 counting only the distinct ones).

The product of its digits is 7776, while the sum is 35.

The square root of 81312992 is about 9017.3716791535. The cubic root of 81312992 is about 433.2314542876.

The spelling of 81312992 in words is "eighty-one million, three hundred twelve thousand, nine hundred ninety-two".