664788 has 12 divisors (see below), whose sum is σ = 1551200. Its totient is φ = 221592.

The previous prime is 664777. The next prime is 664789. The reversal of 664788 is 887466.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664789) by changing a digit.

664788 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, 27688 + ... + 27711.

2⁶⁶⁴⁷⁸⁸ is an apocalyptic number.

It is an amenable number.

664788 is an abundant number, since it is smaller than the sum of its proper divisors (886412).

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

664788 is a wasteful number, since it uses less digits than its factorization.

664788 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55406 (or 55404 counting only the distinct ones).

The product of its digits is 64512, while the sum is 39.

The square root of 664788 is about 815.3453256136. The cubic root of 664788 is about 87.2759109476.

The spelling of 664788 in words is "six hundred sixty-four thousand, seven hundred eighty-eight".