664621656 has 16 divisors (see below), whose sum is σ = 1661554200. Its totient is φ = 221540544.

The previous prime is 664621621. The next prime is 664621669. The reversal of 664621656 is 656126466.

It is a happy number.

664621656 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, 13846261 + ... + 13846308.

Almost surely, 2^664621656 is an apocalyptic number.

It is an amenable number.

664621656 is an abundant number, since it is smaller than the sum of its proper divisors (996932544).

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

664621656 is a wasteful number, since it uses less digits than its factorization.

664621656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27692578 (or 27692574 counting only the distinct ones).

The product of its digits is 311040, while the sum is 42.

The square root of 664621656 is about 25780.2570972440. The cubic root of 664621656 is about 872.6863091490.

The spelling of 664621656 in words is "six hundred sixty-four million, six hundred twenty-one thousand, six hundred fifty-six".