664947664 has 80 divisors (see below), whose sum is σ = 1381161600. Its totient is φ = 309450240.

The previous prime is 664947649. The next prime is 664947671. The reversal of 664947664 is 466749466.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3673654 + ... + 3673834.

It is an arithmetic number, because the mean of its divisors is an integer number (17264520).

Almost surely, 2^664947664 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 664947664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (690580800).

664947664 is an abundant number, since it is smaller than the sum of its proper divisors (716213936).

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

664947664 is a wasteful number, since it uses less digits than its factorization.

664947664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 428 (or 422 counting only the distinct ones).

The product of its digits is 5225472, while the sum is 52.

The square root of 664947664 is about 25786.5791449738. The cubic root of 664947664 is about 872.8289748850.

The spelling of 664947664 in words is "six hundred sixty-four million, nine hundred forty-seven thousand, six hundred sixty-four".