81979994804 has 48 divisors (see below), whose sum is σ = 146754874560. Its totient is φ = 40060500480.

The previous prime is 81979994753. The next prime is 81979994809. The reversal of 81979994804 is 40849997918.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81979994809) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 42453719 + ... + 42455649.

It is an arithmetic number, because the mean of its divisors is an integer number (3057393220).

Almost surely, 2^81979994804 is an apocalyptic number.

It is an amenable number.

81979994804 is a deficient number, since it is larger than the sum of its proper divisors (64774879756).

81979994804 is a wasteful number, since it uses less digits than its factorization.

81979994804 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3168 (or 3166 counting only the distinct ones).

The product of its (nonzero) digits is 47029248, while the sum is 68.

The spelling of 81979994804 in words is "eighty-one billion, nine hundred seventy-nine million, nine hundred ninety-four thousand, eight hundred four".