644222256 has 20 divisors (see below), whose sum is σ = 1664240952. Its totient is φ = 214740736.

The previous prime is 644222233. The next prime is 644222291. The reversal of 644222256 is 652222446.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6710601 + ... + 6710696.

Almost surely, 2^644222256 is an apocalyptic number.

It is an amenable number.

644222256 is an abundant number, since it is smaller than the sum of its proper divisors (1020018696).

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

644222256 is a wasteful number, since it uses less digits than its factorization.

644222256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13421308 (or 13421302 counting only the distinct ones).

The product of its digits is 46080, while the sum is 33.

The square root of 644222256 is about 25381.5337598026. The cubic root of 644222256 is about 863.6648434278.

The spelling of 644222256 in words is "six hundred forty-four million, two hundred twenty-two thousand, two hundred fifty-six".