644444875025 has 18 divisors (see below), whose sum is σ = 929578854150. Its totient is φ = 441905056320.

The previous prime is 644444875013. The next prime is 644444875033. The reversal of 644444875025 is 520578444446.

It can be written as a sum of positive squares in 3 ways, for example, as 740329681 + 643704545344 = 27209^2 + 802312^2 .

It is not a de Polignac number, because 644444875025 - 2¹⁰ = 644444874001 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 263037500 + ... + 263039949.

It is an arithmetic number, because the mean of its divisors is an integer number (51643269675).

Almost surely, 2^644444875025 is an apocalyptic number.

It is an amenable number.

644444875025 is a deficient number, since it is larger than the sum of its proper divisors (285133979125).

644444875025 is a wasteful number, since it uses less digits than its factorization.

644444875025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 526077473 (or 526077461 counting only the distinct ones).

The product of its (nonzero) digits is 17203200, while the sum is 53.

The spelling of 644444875025 in words is "six hundred forty-four billion, four hundred forty-four million, eight hundred seventy-five thousand, twenty-five".