644372856 has 48 divisors (see below), whose sum is σ = 1747193760. Its totient is φ = 214542720.

The previous prime is 644372819. The next prime is 644372857. The reversal of 644372856 is 658273446.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644372857) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 63921 + ... + 73311.

It is an arithmetic number, because the mean of its divisors is an integer number (36399870).

Almost surely, 2^644372856 is an apocalyptic number.

It is an amenable number.

644372856 is an abundant number, since it is smaller than the sum of its proper divisors (1102820904).

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

644372856 is a wasteful number, since it uses less digits than its factorization.

644372856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10356 (or 10349 counting only the distinct ones).

The product of its digits is 967680, while the sum is 45.

The square root of 644372856 is about 25384.5003102287. The cubic root of 644372856 is about 863.7321379007.

The spelling of 644372856 in words is "six hundred forty-four million, three hundred seventy-two thousand, eight hundred fifty-six".