644118380 has 12 divisors (see below), whose sum is σ = 1352648640. Its totient is φ = 257647344.

The previous prime is 644118367. The next prime is 644118437. The reversal of 644118380 is 83811446.

It is a self number, because there is not a number n which added to its sum of digits gives 644118380.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16102940 + ... + 16102979.

It is an arithmetic number, because the mean of its divisors is an integer number (112720720).

Almost surely, 2^644118380 is an apocalyptic number.

It is an amenable number.

644118380 is an abundant number, since it is smaller than the sum of its proper divisors (708530260).

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

644118380 is a wasteful number, since it uses less digits than its factorization.

644118380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32205928 (or 32205926 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 35.

The square root of 644118380 is about 25379.4873864702. The cubic root of 644118380 is about 863.6184211097.

The spelling of 644118380 in words is "six hundred forty-four million, one hundred eighteen thousand, three hundred eighty".