81409708664 has 32 divisors (see below), whose sum is σ = 161786898720. Its totient is φ = 38271415296.

The previous prime is 81409708651. The next prime is 81409708687. The reversal of 81409708664 is 46680790418.

It is a congruent number.

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, 170789 + ... + 438164.

It is an arithmetic number, because the mean of its divisors is an integer number (5055840585).

Almost surely, 2^81409708664 is an apocalyptic number.

It is an amenable number.

81409708664 is a deficient number, since it is larger than the sum of its proper divisors (80377190056).

81409708664 is a wasteful number, since it uses less digits than its factorization.

81409708664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 609959 (or 609955 counting only the distinct ones).

The product of its (nonzero) digits is 2322432, while the sum is 53.

The spelling of 81409708664 in words is "eighty-one billion, four hundred nine million, seven hundred eight thousand, six hundred sixty-four".