644969328 has 20 divisors (see below), whose sum is σ = 1666170888. Its totient is φ = 214989760.

The previous prime is 644969317. The next prime is 644969329. The reversal of 644969328 is 823969446.

644969328 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644969329) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6718383 + ... + 6718478.

Almost surely, 2^644969328 is an apocalyptic number.

It is an amenable number.

644969328 is an abundant number, since it is smaller than the sum of its proper divisors (1021201560).

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

644969328 is a wasteful number, since it uses less digits than its factorization.

644969328 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13436872 (or 13436866 counting only the distinct ones).

The product of its digits is 2239488, while the sum is 51.

The square root of 644969328 is about 25396.2463368113. The cubic root of 644969328 is about 863.9985639551.

The spelling of 644969328 in words is "six hundred forty-four million, nine hundred sixty-nine thousand, three hundred twenty-eight".