644676125 has 16 divisors (see below), whose sum is σ = 851885424. Its totient is φ = 485401600.

The previous prime is 644676089. The next prime is 644676133. The reversal of 644676125 is 521676446.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 318765316 + 325910809 = 17854^2 + 18053^2 .

It is not a de Polignac number, because 644676125 - 2⁸ = 644675869 is a prime.

It is a super-2 number, since 2×644676125² = 831214612290031250, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 149564 + ... + 153813.

It is an arithmetic number, because the mean of its divisors is an integer number (53242839).

Almost surely, 2^644676125 is an apocalyptic number.

It is an amenable number.

644676125 is a deficient number, since it is larger than the sum of its proper divisors (207209299).

644676125 is a wasteful number, since it uses less digits than its factorization.

644676125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 303409 (or 303399 counting only the distinct ones).

The product of its digits is 241920, while the sum is 41.

The square root of 644676125 is about 25390.4731149303. The cubic root of 644676125 is about 863.8676195535.

The spelling of 644676125 in words is "six hundred forty-four million, six hundred seventy-six thousand, one hundred twenty-five".