644763344 has 10 divisors (see below), whose sum is σ = 1249229010. Its totient is φ = 322381664.

The previous prime is 644763341. The next prime is 644763349. The reversal of 644763344 is 443367446.

It is a happy number.

644763344 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 475763344 + 169000000 = 21812^2 + 13000^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644763341) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20148839 + ... + 20148870.

It is an arithmetic number, because the mean of its divisors is an integer number (124922901).

Almost surely, 2^644763344 is an apocalyptic number.

It is an amenable number.

644763344 is a deficient number, since it is larger than the sum of its proper divisors (604465666).

644763344 is a wasteful number, since it uses less digits than its factorization.

644763344 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40297717 (or 40297711 counting only the distinct ones).

The product of its digits is 580608, while the sum is 41.

The square root of 644763344 is about 25392.1906105007. The cubic root of 644763344 is about 863.9065756894.

The spelling of 644763344 in words is "six hundred forty-four million, seven hundred sixty-three thousand, three hundred forty-four".