81556074812 has 12 divisors (see below), whose sum is σ = 142725918720. Its totient is φ = 40777240896.

The previous prime is 81556074781. The next prime is 81556074823. The reversal of 81556074812 is 21847065518.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 72389 + ... + 410307.

It is an arithmetic number, because the mean of its divisors is an integer number (11893826560).

Almost surely, 2^81556074812 is an apocalyptic number.

It is an amenable number.

81556074812 is a deficient number, since it is larger than the sum of its proper divisors (61169843908).

81556074812 is a wasteful number, since it uses less digits than its factorization.

81556074812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 398260 (or 398258 counting only the distinct ones).

The product of its (nonzero) digits is 537600, while the sum is 47.

The spelling of 81556074812 in words is "eighty-one billion, five hundred fifty-six million, seventy-four thousand, eight hundred twelve".