644960392 has 16 divisors (see below), whose sum is σ = 1232118540. Its totient is φ = 316395456.

The previous prime is 644960387. The next prime is 644960413. The reversal of 644960392 is 293069446.

It can be written as a sum of positive squares in 2 ways, for example, as 625300036 + 19660356 = 25006^2 + 4434^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 760143 + ... + 760990.

Almost surely, 2^644960392 is an apocalyptic number.

It is an amenable number.

644960392 is a deficient number, since it is larger than the sum of its proper divisors (587158148).

644960392 is a wasteful number, since it uses less digits than its factorization.

644960392 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1521192 (or 1521188 counting only the distinct ones).

The product of its (nonzero) digits is 279936, while the sum is 43.

The square root of 644960392 is about 25396.0704046906. The cubic root of 644960392 is about 863.9945737256.

The spelling of 644960392 in words is "six hundred forty-four million, nine hundred sixty thousand, three hundred ninety-two".