664656 has 40 divisors (see below), whose sum is σ = 1752864. Its totient is φ = 216960.

The previous prime is 664633. The next prime is 664661. The reversal of 664656 is 656466.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2815 + ... + 3041.

2⁶⁶⁴⁶⁵⁶ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 664656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (876432).

664656 is an abundant number, since it is smaller than the sum of its proper divisors (1088208).

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

664656 is a wasteful number, since it uses less digits than its factorization.

664656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 299 (or 293 counting only the distinct ones).

The product of its digits is 25920, while the sum is 33.

The square root of 664656 is about 815.2643742983. The cubic root of 664656 is about 87.2701340770.

The spelling of 664656 in words is "six hundred sixty-four thousand, six hundred fifty-six".