644332005 has 48 divisors (see below), whose sum is σ = 1205642880. Its totient is φ = 317353344.

The previous prime is 644331967. The next prime is 644332019. The reversal of 644332005 is 500233446.

It is not a de Polignac number, because 644332005 - 2⁸ = 644331749 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 644332005.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 19282 + ... + 40748.

It is an arithmetic number, because the mean of its divisors is an integer number (25117560).

Almost surely, 2^644332005 is an apocalyptic number.

It is an amenable number.

644332005 is a deficient number, since it is larger than the sum of its proper divisors (561310875).

644332005 is a wasteful number, since it uses less digits than its factorization.

644332005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21530 (or 21527 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 27.

The square root of 644332005 is about 25383.6956529186. The cubic root of 644332005 is about 863.7138849762.

The spelling of 644332005 in words is "six hundred forty-four million, three hundred thirty-two thousand, five".