644923296 has 60 divisors (see below), whose sum is σ = 1896709122. Its totient is φ = 214973568.

The previous prime is 644923291. The next prime is 644923333. The reversal of 644923296 is 692329446.

644923296 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., 633226896 + 11696400 = 25164^2 + 3420^2 .

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (644923291) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 121815 + ... + 126998.

Almost surely, 2^644923296 is an apocalyptic number.

It is an amenable number.

644923296 is an abundant number, since it is smaller than the sum of its proper divisors (1251785826).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644923296 is a wasteful number, since it uses less digits than its factorization.

644923296 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 248835 (or 248818 counting only the distinct ones).

The product of its digits is 559872, while the sum is 45.

The square root of 644923296 is about 25395.3400449768. The cubic root of 644923296 is about 863.9780086995.

The spelling of 644923296 in words is "six hundred forty-four million, nine hundred twenty-three thousand, two hundred ninety-six".