81865964 has 12 divisors (see below), whose sum is σ = 144228000. Its totient is φ = 40657968.

The previous prime is 81865951. The next prime is 81865967. The reversal of 81865964 is 46956818.

It is not an unprimeable number, because it can be changed into a prime (81865967) 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 3 ways as a sum of consecutive naturals, for example, 68084 + ... + 69275.

It is an arithmetic number, because the mean of its divisors is an integer number (12019000).

Almost surely, 2^81865964 is an apocalyptic number.

It is an amenable number.

81865964 is a deficient number, since it is larger than the sum of its proper divisors (62362036).

81865964 is a wasteful number, since it uses less digits than its factorization.

81865964 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137512 (or 137510 counting only the distinct ones).

The product of its digits is 414720, while the sum is 47.

The square root of 81865964 is about 9047.9812112979. The cubic root of 81865964 is about 434.2113052878.

The spelling of 81865964 in words is "eighty-one million, eight hundred sixty-five thousand, nine hundred sixty-four".