644977872 has 120 divisors (see below), whose sum is σ = 2250480960. Its totient is φ = 167523840.

The previous prime is 644977843. The next prime is 644977873. The reversal of 644977872 is 278779446.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644977873) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 17997 + ... + 40172.

It is an arithmetic number, because the mean of its divisors is an integer number (18754008).

Almost surely, 2^644977872 is an apocalyptic number.

It is an amenable number.

644977872 is an abundant number, since it is smaller than the sum of its proper divisors (1605503088).

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

644977872 is a wasteful number, since it uses less digits than its factorization.

644977872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58201 (or 58192 counting only the distinct ones).

The product of its digits is 4741632, while the sum is 54.

The square root of 644977872 is about 25396.4145500895. The cubic root of 644977872 is about 864.0023791087.

The spelling of 644977872 in words is "six hundred forty-four million, nine hundred seventy-seven thousand, eight hundred seventy-two".