644626460 has 12 divisors (see below), whose sum is σ = 1353715608. Its totient is φ = 257850576.

The previous prime is 644626441. The next prime is 644626481. The reversal of 644626460 is 64626446.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16115642 + ... + 16115681.

It is an arithmetic number, because the mean of its divisors is an integer number (112809634).

Almost surely, 2^644626460 is an apocalyptic number.

It is an amenable number.

644626460 is an abundant number, since it is smaller than the sum of its proper divisors (709089148).

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

644626460 is a wasteful number, since it uses less digits than its factorization.

644626460 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32231332 (or 32231330 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 38.

The square root of 644626460 is about 25389.4950717812. The cubic root of 644626460 is about 863.8454352424.

The spelling of 644626460 in words is "six hundred forty-four million, six hundred twenty-six thousand, four hundred sixty".