644974900 has 36 divisors (see below), whose sum is σ = 1481928588. Its totient is φ = 242813440.

The previous prime is 644974879. The next prime is 644974919. The reversal of 644974900 is 9479446.

It can be written as a sum of positive squares in 6 ways, for example, as 63393444 + 581581456 = 7962^2 + 24116^2 .

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 11 ways as a sum of consecutive naturals, for example, 187999 + ... + 191398.

It is an arithmetic number, because the mean of its divisors is an integer number (41164683).

Almost surely, 2^644974900 is an apocalyptic number.

It is an amenable number.

644974900 is an abundant number, since it is smaller than the sum of its proper divisors (836953688).

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

644974900 is a wasteful number, since it uses less digits than its factorization.

644974900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 379428 (or 379421 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 43.

The square root of 644974900 is about 25396.3560378256. The cubic root of 644974900 is about 864.0010520249.

The spelling of 644974900 in words is "six hundred forty-four million, nine hundred seventy-four thousand, nine hundred".