664556 has 12 divisors (see below), whose sum is σ = 1174992. Its totient is φ = 328848.

The previous prime is 664549. The next prime is 664561. The reversal of 664556 is 655466.

664556 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

664556 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 395 + ... + 1218.

It is an arithmetic number, because the mean of its divisors is an integer number (97916).

2⁶⁶⁴⁵⁵⁶ is an apocalyptic number.

It is an amenable number.

664556 is a deficient number, since it is larger than the sum of its proper divisors (510436).

664556 is a wasteful number, since it uses less digits than its factorization.

664556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1720 (or 1718 counting only the distinct ones).

The product of its digits is 21600, while the sum is 32.

The square root of 664556 is about 815.2030421926. The cubic root of 664556 is about 87.2657571506.

The spelling of 664556 in words is "six hundred sixty-four thousand, five hundred fifty-six".