644100625 has 80 divisors (see below), whose sum is σ = 991482624. Its totient is φ = 408672000.

The previous prime is 644100619. The next prime is 644100649. The reversal of 644100625 is 526001446.

It is not a de Polignac number, because 644100625 - 2⁷ = 644100497 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 644100593 and 644100602.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 3723039 + ... + 3723211.

Almost surely, 2^644100625 is an apocalyptic number.

It is an amenable number.

644100625 is a deficient number, since it is larger than the sum of its proper divisors (347381999).

644100625 is a wasteful number, since it uses less digits than its factorization.

644100625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 260 (or 245 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 28.

The square root of 644100625 is about 25379.1375937009. The cubic root of 644100625 is about 863.6104858778.

It can be divided in two parts, 644 and 100625, that multiplied together give a square (64802500 = 8050²).

The spelling of 644100625 in words is "six hundred forty-four million, one hundred thousand, six hundred twenty-five".