644135625 has 240 divisors, whose sum is σ = 1495771200. Its totient is φ = 272160000.

The previous prime is 644135623. The next prime is 644135651. The reversal of 644135625 is 526531446.

644135625 is a `hidden beast` number, since 644 + 1 + 3 + 5 + 6 + 2 + 5 = 666.

644135625 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 644135625 - 2¹ = 644135623 is a prime.

Its product of digits (86400) is a multiple of the sum of its prime divisors (75).

It is a self number, because there is not a number n which added to its sum of digits gives 644135625.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644135621) by changing a digit.

It is a polite number, since it can be written in 239 ways as a sum of consecutive naturals, for example, 15710605 + ... + 15710645.

It is an arithmetic number, because the mean of its divisors is an integer number (6232380).

Almost surely, 2^644135625 is an apocalyptic number.

It is an amenable number.

644135625 is an abundant number, since it is smaller than the sum of its proper divisors (851635575).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644135625 is a wasteful number, since it uses less digits than its factorization.

644135625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103 (or 75 counting only the distinct ones).

The product of its digits is 86400, while the sum is 36.

The square root of 644135625 is about 25379.8271270708. The cubic root of 644135625 is about 863.6261282679.

The spelling of 644135625 in words is "six hundred forty-four million, one hundred thirty-five thousand, six hundred twenty-five".