644377420 has 12 divisors (see below), whose sum is σ = 1353192624. Its totient is φ = 257750960.

The previous prime is 644377417. The next prime is 644377421. The reversal of 644377420 is 24773446.

It is a self number, because there is not a number n which added to its sum of digits gives 644377420.

It is not an unprimeable number, because it can be changed into a prime (644377421) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16109416 + ... + 16109455.

It is an arithmetic number, because the mean of its divisors is an integer number (112766052).

Almost surely, 2^644377420 is an apocalyptic number.

It is an amenable number.

644377420 is an abundant number, since it is smaller than the sum of its proper divisors (708815204).

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

644377420 is a wasteful number, since it uses less digits than its factorization.

644377420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32218880 (or 32218878 counting only the distinct ones).

The product of its (nonzero) digits is 112896, while the sum is 37.

The square root of 644377420 is about 25384.5902074467. The cubic root of 644377420 is about 863.7341771259.

The spelling of 644377420 in words is "six hundred forty-four million, three hundred seventy-seven thousand, four hundred twenty".