644313918 has 8 divisors (see below), whose sum is σ = 1288627848. Its totient is φ = 214771304.

The previous prime is 644313899. The next prime is 644313919. The reversal of 644313918 is 819313446.

It is a sphenic number, since it is the product of 3 distinct primes.

644313918 is an admirable number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644313919) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 53692821 + ... + 53692832.

It is an arithmetic number, because the mean of its divisors is an integer number (161078481).

Almost surely, 2^644313918 is an apocalyptic number.

644313918 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

644313918 is a wasteful number, since it uses less digits than its factorization.

644313918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107385658.

The product of its digits is 62208, while the sum is 39.

The square root of 644313918 is about 25383.3393784191. The cubic root of 644313918 is about 863.7058031493.

The spelling of 644313918 in words is "six hundred forty-four million, three hundred thirteen thousand, nine hundred eighteen".