644704973 has 16 divisors (see below), whose sum is σ = 735267456. Its totient is φ = 559563840.

The previous prime is 644704967. The next prime is 644704987. The reversal of 644704973 is 379407446.

It is not a de Polignac number, because 644704973 - 2⁸ = 644704717 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644704993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 153011 + ... + 157167.

It is an arithmetic number, because the mean of its divisors is an integer number (45954216).

Almost surely, 2^644704973 is an apocalyptic number.

It is an amenable number.

644704973 is a deficient number, since it is larger than the sum of its proper divisors (90562483).

644704973 is a wasteful number, since it uses less digits than its factorization.

644704973 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4804.

The product of its (nonzero) digits is 508032, while the sum is 44.

The square root of 644704973 is about 25391.0411956658. The cubic root of 644704973 is about 863.8805048253.

The spelling of 644704973 in words is "six hundred forty-four million, seven hundred four thousand, nine hundred seventy-three".