664491904 has 64 divisors (see below), whose sum is σ = 1352458800. Its totient is φ = 325140480.

The previous prime is 664491881. The next prime is 664491923. The reversal of 664491904 is 409194466.

664491904 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (64).

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, 1353099 + ... + 1353589.

Almost surely, 2^664491904 is an apocalyptic number.

664491904 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 664491904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (676229400).

664491904 is an abundant number, since it is smaller than the sum of its proper divisors (687966896).

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

664491904 is a wasteful number, since it uses less digits than its factorization.

664491904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 711 (or 699 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 43.

The square root of 664491904 is about 25777.7404750688. The cubic root of 664491904 is about 872.6295148498.

The spelling of 664491904 in words is "six hundred sixty-four million, four hundred ninety-one thousand, nine hundred four".