81784571664 has 40 divisors (see below), whose sum is σ = 211288298112. Its totient is φ = 27260041600.

The previous prime is 81784571657. The next prime is 81784571681. The reversal of 81784571664 is 46617548718.

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, 1180777 + ... + 1248119.

Almost surely, 2^81784571664 is an apocalyptic number.

It is an amenable number.

81784571664 is an abundant number, since it is smaller than the sum of its proper divisors (129503726448).

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

81784571664 is a wasteful number, since it uses less digits than its factorization.

81784571664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92655 (or 92649 counting only the distinct ones).

The product of its digits is 9031680, while the sum is 57.

The spelling of 81784571664 in words is "eighty-one billion, seven hundred eighty-four million, five hundred seventy-one thousand, six hundred sixty-four".