644225725 has 48 divisors (see below), whose sum is σ = 968937984. Its totient is φ = 418464000.

The previous prime is 644225719. The next prime is 644225737. The reversal of 644225725 is 527522446.

It is not a de Polignac number, because 644225725 - 2³ = 644225717 is a prime.

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 107919 + ... + 113731.

It is an arithmetic number, because the mean of its divisors is an integer number (20186208).

Almost surely, 2^644225725 is an apocalyptic number.

644225725 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

644225725 is a deficient number, since it is larger than the sum of its proper divisors (324712259).

644225725 is a wasteful number, since it uses less digits than its factorization.

644225725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5878 (or 5873 counting only the distinct ones).

The product of its digits is 134400, while the sum is 37.

The square root of 644225725 is about 25381.6020967944. The cubic root of 644225725 is about 863.6663936423. Note that the first 3 decimals are identical.

The spelling of 644225725 in words is "six hundred forty-four million, two hundred twenty-five thousand, seven hundred twenty-five".