644256792 has 48 divisors (see below), whose sum is σ = 1749930000. Its totient is φ = 214128576.

The previous prime is 644256773. The next prime is 644256797. The reversal of 644256792 is 297652446.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644256797) 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, 12309 + ... + 37947.

It is an arithmetic number, because the mean of its divisors is an integer number (36456875).

Almost surely, 2^644256792 is an apocalyptic number.

It is an amenable number.

644256792 is an abundant number, since it is smaller than the sum of its proper divisors (1105673208).

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

644256792 is a wasteful number, since it uses less digits than its factorization.

644256792 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26000 (or 25993 counting only the distinct ones).

The product of its digits is 725760, while the sum is 45.

The square root of 644256792 is about 25382.2140878214. The cubic root of 644256792 is about 863.6802765053.

It can be divided in two parts, 64425 and 6792, that added together give a palindrome (71217).

The spelling of 644256792 in words is "six hundred forty-four million, two hundred fifty-six thousand, seven hundred ninety-two".