644389625 has 16 divisors (see below), whose sum is σ = 877309056. Its totient is φ = 468646000.

The previous prime is 644389609. The next prime is 644389633. The reversal of 644389625 is 526983446.

It is not a de Polignac number, because 644389625 - 2⁴ = 644389609 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 644389625.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 232949 + ... + 235698.

It is an arithmetic number, because the mean of its divisors is an integer number (54831816).

Almost surely, 2^644389625 is an apocalyptic number.

It is an amenable number.

644389625 is a deficient number, since it is larger than the sum of its proper divisors (232919431).

644389625 is a wasteful number, since it uses less digits than its factorization.

644389625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 468673 (or 468663 counting only the distinct ones).

The product of its digits is 1244160, while the sum is 47.

The square root of 644389625 is about 25384.8306080620. The cubic root of 644389625 is about 863.7396303530.

The spelling of 644389625 in words is "six hundred forty-four million, three hundred eighty-nine thousand, six hundred twenty-five".