81861592 has 16 divisors (see below), whose sum is σ = 156756960. Its totient is φ = 40059744.

The previous prime is 81861581. The next prime is 81861599. The reversal of 81861592 is 29516818.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81861599) 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, 108483 + ... + 109234.

It is an arithmetic number, because the mean of its divisors is an integer number (9797310).

Almost surely, 2^81861592 is an apocalyptic number.

It is an amenable number.

81861592 is a deficient number, since it is larger than the sum of its proper divisors (74895368).

81861592 is a wasteful number, since it uses less digits than its factorization.

81861592 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 217770 (or 217766 counting only the distinct ones).

The product of its digits is 34560, while the sum is 40.

The square root of 81861592 is about 9047.7396072168. The cubic root of 81861592 is about 434.2035755569.

The spelling of 81861592 in words is "eighty-one million, eight hundred sixty-one thousand, five hundred ninety-two".