644438336 has 14 divisors (see below), whose sum is σ = 1278807450. Its totient is φ = 322219136.

The previous prime is 644438309. The next prime is 644438351. The reversal of 644438336 is 633834446.

It can be written as a sum of positive squares in only one way, i.e., 643129600 + 1308736 = 25360^2 + 1144^2 .

It is a junction number, because it is equal to n+sod(n) for n = 644438293 and 644438302.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5034611 + ... + 5034738.

Almost surely, 2^644438336 is an apocalyptic number.

It is an amenable number.

644438336 is a deficient number, since it is larger than the sum of its proper divisors (634369114).

644438336 is a wasteful number, since it uses less digits than its factorization.

644438336 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10069361 (or 10069351 counting only the distinct ones).

The product of its digits is 497664, while the sum is 41.

The square root of 644438336 is about 25385.7900408870. The cubic root of 644438336 is about 863.7613938738.

The spelling of 644438336 in words is "six hundred forty-four million, four hundred thirty-eight thousand, three hundred thirty-six".