81977894866 has 32 divisors (see below), whose sum is σ = 142311923712. Its totient is φ = 34691576400.

The previous prime is 81977894857. The next prime is 81977894899. The reversal of 81977894866 is 66849877918.

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, 236935 + ... + 469141.

It is an arithmetic number, because the mean of its divisors is an integer number (4447247616).

Almost surely, 2^81977894866 is an apocalyptic number.

81977894866 is a deficient number, since it is larger than the sum of its proper divisors (60334028846).

81977894866 is a wasteful number, since it uses less digits than its factorization.

81977894866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 232534.

The product of its digits is 292626432, while the sum is 73.

The spelling of 81977894866 in words is "eighty-one billion, nine hundred seventy-seven million, eight hundred ninety-four thousand, eight hundred sixty-six".