644427168 has 96 divisors (see below), whose sum is σ = 2109058560. Its totient is φ = 167381760.

The previous prime is 644427139. The next prime is 644427191. The reversal of 644427168 is 861724446.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a nude number because it is divisible by every one of its digits.

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 15 ways as a sum of consecutive naturals, for example, 36198 + ... + 50981.

It is an arithmetic number, because the mean of its divisors is an integer number (21969360).

Almost surely, 2^644427168 is an apocalyptic number.

It is an amenable number.

644427168 is an abundant number, since it is smaller than the sum of its proper divisors (1464631392).

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

644427168 is a wasteful number, since it uses less digits than its factorization.

644427168 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87210 (or 87202 counting only the distinct ones).

The product of its digits is 258048, while the sum is 42.

The square root of 644427168 is about 25385.5700743552. The cubic root of 644427168 is about 863.7564042353.

The spelling of 644427168 in words is "six hundred forty-four million, four hundred twenty-seven thousand, one hundred sixty-eight".