644833225 has 36 divisors (see below), whose sum is σ = 835352784. Its totient is φ = 493692480.

The previous prime is 644833181. The next prime is 644833237. The reversal of 644833225 is 522338446.

It is not a de Polignac number, because 644833225 - 2⁷ = 644833097 is a prime.

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

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 2840562 + ... + 2840788.

It is an arithmetic number, because the mean of its divisors is an integer number (23204244).

Almost surely, 2^644833225 is an apocalyptic number.

It is an amenable number.

644833225 is a deficient number, since it is larger than the sum of its proper divisors (190519559).

644833225 is a wasteful number, since it uses less digits than its factorization.

644833225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 394 (or 352 counting only the distinct ones).

The product of its digits is 138240, while the sum is 37.

The square root of 644833225 is about 25393.5666065246. The cubic root of 644833225 is about 863.9377853186.

The spelling of 644833225 in words is "six hundred forty-four million, eight hundred thirty-three thousand, two hundred twenty-five".