81915406825728 has 72 divisors (see below), whose sum is σ = 249159362444608. Its totient is φ = 23404401948672.

The previous prime is 81915406825697. The next prime is 81915406825751. The reversal of 81915406825728 is 82752860451918.

It is a Smith number, since the sum of its digits (66) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7618615051 + ... + 7618625802.

Almost surely, 2^{81915406825728} is an apocalyptic number.

It is an amenable number.

81915406825728 is an abundant number, since it is smaller than the sum of its proper divisors (167243955618880).

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

81915406825728 is a wasteful number, since it uses less digits than its factorization.

81915406825728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15237240879 (or 15237240865 counting only the distinct ones).

The product of its (nonzero) digits is 77414400, while the sum is 66.

The spelling of 81915406825728 in words is "eighty-one trillion, nine hundred fifteen billion, four hundred six million, eight hundred twenty-five thousand, seven hundred twenty-eight".