66931664 has 10 divisors (see below), whose sum is σ = 129680130. Its totient is φ = 33465824.

The previous prime is 66931643. The next prime is 66931673. The reversal of 66931664 is 46613966.

It can be written as a sum of positive squares in only one way, i.e., 59598400 + 7333264 = 7720^2 + 2708^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2091599 + ... + 2091630.

It is an arithmetic number, because the mean of its divisors is an integer number (12968013).

Almost surely, 2^66931664 is an apocalyptic number.

It is an amenable number.

66931664 is a deficient number, since it is larger than the sum of its proper divisors (62748466).

66931664 is a wasteful number, since it uses less digits than its factorization.

66931664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4183237 (or 4183231 counting only the distinct ones).

The product of its digits is 139968, while the sum is 41.

The square root of 66931664 is about 8181.1774213740. The cubic root of 66931664 is about 406.0166785192.

The spelling of 66931664 in words is "sixty-six million, nine hundred thirty-one thousand, six hundred sixty-four".