644635460 has 48 divisors (see below), whose sum is σ = 1588952064. Its totient is φ = 215042688.

The previous prime is 644635451. The next prime is 644635471. The reversal of 644635460 is 64536446.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 57044 + ... + 67403.

It is an arithmetic number, because the mean of its divisors is an integer number (33103168).

Almost surely, 2^644635460 is an apocalyptic number.

It is an amenable number.

644635460 is an abundant number, since it is smaller than the sum of its proper divisors (944316604).

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

644635460 is a wasteful number, since it uses less digits than its factorization.

644635460 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124500 (or 124498 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 38.

The square root of 644635460 is about 25389.6723098192. The cubic root of 644635460 is about 863.8494554377.

The spelling of 644635460 in words is "six hundred forty-four million, six hundred thirty-five thousand, four hundred sixty".