644366725 has 12 divisors (see below), whose sum is σ = 846016164. Its totient is φ = 485169920.

The previous prime is 644366719. The next prime is 644366731. The reversal of 644366725 is 527663446.

It is an interprime number because it is at equal distance from previous prime (644366719) and next prime (644366731).

It can be written as a sum of positive squares in 6 ways, for example, as 10233601 + 634133124 = 3199^2 + 25182^2 .

It is not a de Polignac number, because 644366725 - 2⁹ = 644366213 is a prime.

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 (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 757654 + ... + 758503.

It is an arithmetic number, because the mean of its divisors is an integer number (70501347).

Almost surely, 2^644366725 is an apocalyptic number.

It is an amenable number.

644366725 is a deficient number, since it is larger than the sum of its proper divisors (201649439).

644366725 is a wasteful number, since it uses less digits than its factorization.

644366725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1516184 (or 1516179 counting only the distinct ones).

The product of its digits is 725760, while the sum is 43.

The square root of 644366725 is about 25384.3795472728. The cubic root of 644366725 is about 863.7293985144.

The spelling of 644366725 in words is "six hundred forty-four million, three hundred sixty-six thousand, seven hundred twenty-five".