644478464 has 40 divisors (see below), whose sum is σ = 1471663248. Its totient is φ = 276203520.

The previous prime is 644478451. The next prime is 644478479. The reversal of 644478464 is 464874446.

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, 86327 + ... + 93494.

Almost surely, 2^644478464 is an apocalyptic number.

644478464 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

644478464 is an abundant number, since it is smaller than the sum of its proper divisors (827184784).

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

644478464 is an equidigital number, since it uses as much as digits as its factorization.

644478464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179846 (or 179830 counting only the distinct ones).

The product of its digits is 2064384, while the sum is 47.

The square root of 644478464 is about 25386.5803920103. The cubic root of 644478464 is about 863.7793217839.

The spelling of 644478464 in words is "six hundred forty-four million, four hundred seventy-eight thousand, four hundred sixty-four".