664391664 has 60 divisors (see below), whose sum is σ = 1861134600. Its totient is φ = 221254272.

The previous prime is 664391633. The next prime is 664391683. The reversal of 664391664 is 466193466.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 256327 + ... + 258905.

It is an arithmetic number, because the mean of its divisors is an integer number (31018910).

Almost surely, 2^664391664 is an apocalyptic number.

It is an amenable number.

664391664 is an abundant number, since it is smaller than the sum of its proper divisors (1196742936).

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

664391664 is a wasteful number, since it uses less digits than its factorization.

664391664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4382 (or 4373 counting only the distinct ones).

The product of its digits is 559872, while the sum is 45.

The square root of 664391664 is about 25775.7960885789. The cubic root of 664391664 is about 872.5856333112.

The spelling of 664391664 in words is "six hundred sixty-four million, three hundred ninety-one thousand, six hundred sixty-four".