664864 has 24 divisors (see below), whose sum is σ = 1330560. Its totient is φ = 326976.

The previous prime is 664849. The next prime is 664879. The reversal of 664864 is 468466.

It is an interprime number because it is at equal distance from previous prime (664849) and next prime (664879).

It is an unprimeable number.

664864 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, 2397 + ... + 2659.

It is an arithmetic number, because the mean of its divisors is an integer number (55440).

2⁶⁶⁴⁸⁶⁴ is an apocalyptic number.

It is an amenable number.

664864 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

664864 is a wasteful number, since it uses less digits than its factorization.

664864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 352 (or 344 counting only the distinct ones).

The product of its digits is 27648, while the sum is 34.

The square root of 664864 is about 815.3919303010. The cubic root of 664864 is about 87.2792366778.

The spelling of 664864 in words is "six hundred sixty-four thousand, eight hundred sixty-four".