81615766804 has 48 divisors (see below), whose sum is σ = 168005307456. Its totient is φ = 34201958400.

The previous prime is 81615766763. The next prime is 81615766829. The reversal of 81615766804 is 40866751618.

It is a super-2 number, since 2×81615766804² (a number of 23 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (52) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (52).

It is a congruent number.

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, 375924 + ... + 551860.

It is an arithmetic number, because the mean of its divisors is an integer number (3500110572).

Almost surely, 2^81615766804 is an apocalyptic number.

It is an amenable number.

81615766804 is an abundant number, since it is smaller than the sum of its proper divisors (86389540652).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81615766804 is a wasteful number, since it uses less digits than its factorization.

81615766804 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 176776 (or 176774 counting only the distinct ones).

The product of its (nonzero) digits is 1935360, while the sum is 52.

The spelling of 81615766804 in words is "eighty-one billion, six hundred fifteen million, seven hundred sixty-six thousand, eight hundred four".