644828256 has 48 divisors (see below), whose sum is σ = 1880751600. Its totient is φ = 214942464.

The previous prime is 644828237. The next prime is 644828273. The reversal of 644828256 is 652828446.

It is a tau number, because it is divible by the number of its divisors (48).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 372301 + ... + 374028.

It is an arithmetic number, because the mean of its divisors is an integer number (39182325).

Almost surely, 2^644828256 is an apocalyptic number.

It is an amenable number.

644828256 is an abundant number, since it is smaller than the sum of its proper divisors (1235923344).

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

644828256 is a wasteful number, since it uses less digits than its factorization.

644828256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 746348 (or 746334 counting only the distinct ones).

The product of its digits is 737280, while the sum is 45.

The square root of 644828256 is about 25393.4687665943. The cubic root of 644828256 is about 863.9355661825.

The spelling of 644828256 in words is "six hundred forty-four million, eight hundred twenty-eight thousand, two hundred fifty-six".