81312970 has 32 divisors (see below), whose sum is σ = 154716480. Its totient is φ = 30683520.

The previous prime is 81312967. The next prime is 81312997. The reversal of 81312970 is 7921318.

It is a super-2 number, since 2×81312970² = 13223598180441800, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 52629 + ... + 54151.

It is an arithmetic number, because the mean of its divisors is an integer number (4834890).

Almost surely, 2^81312970 is an apocalyptic number.

81312970 is a deficient number, since it is larger than the sum of its proper divisors (73403510).

81312970 is a wasteful number, since it uses less digits than its factorization.

81312970 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1830.

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 81312970 is about 9017.3704592858. The cubic root of 81312970 is about 433.2314152159.

The spelling of 81312970 in words is "eighty-one million, three hundred twelve thousand, nine hundred seventy".