644155256 has 32 divisors (see below), whose sum is σ = 1229649600. Its totient is φ = 316293120.

The previous prime is 644155249. The next prime is 644155277. The reversal of 644155256 is 652551446.

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, 119336 + ... + 124616.

It is an arithmetic number, because the mean of its divisors is an integer number (38426550).

Almost surely, 2^644155256 is an apocalyptic number.

It is an amenable number.

644155256 is a deficient number, since it is larger than the sum of its proper divisors (585494344).

644155256 is a wasteful number, since it uses less digits than its factorization.

644155256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5559 (or 5555 counting only the distinct ones).

The product of its digits is 144000, while the sum is 38.

The square root of 644155256 is about 25380.2138682872. The cubic root of 644155256 is about 863.6349016129.

The spelling of 644155256 in words is "six hundred forty-four million, one hundred fifty-five thousand, two hundred fifty-six".