644595992 has 32 divisors (see below), whose sum is σ = 1253340000. Its totient is φ = 310426368.

The previous prime is 644595977. The next prime is 644596013. The reversal of 644595992 is 299595446.

It is a happy number.

It is a Smith number, since the sum of its digits (53) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 98684 + ... + 105012.

It is an arithmetic number, because the mean of its divisors is an integer number (39166875).

Almost surely, 2^644595992 is an apocalyptic number.

It is an amenable number.

644595992 is a deficient number, since it is larger than the sum of its proper divisors (608744008).

644595992 is a wasteful number, since it uses less digits than its factorization.

644595992 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6803 (or 6799 counting only the distinct ones).

The product of its digits is 3499200, while the sum is 53.

The square root of 644595992 is about 25388.8950527588. The cubic root of 644595992 is about 863.8318252636.

The spelling of 644595992 in words is "six hundred forty-four million, five hundred ninety-five thousand, nine hundred ninety-two".