639445025 has 6 divisors (see below), whose sum is σ = 792911862. Its totient is φ = 511556000.

The previous prime is 639444991. The next prime is 639445043. The reversal of 639445025 is 520544936.

It can be written as a sum of positive squares in 3 ways, for example, as 174266401 + 465178624 = 13201^2 + 21568^2 .

It is not a de Polignac number, because 639445025 - 2⁸ = 639444769 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 639445025.

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 5 ways as a sum of consecutive naturals, for example, 12788876 + ... + 12788925.

It is an arithmetic number, because the mean of its divisors is an integer number (132151977).

Almost surely, 2^639445025 is an apocalyptic number.

It is an amenable number.

639445025 is a deficient number, since it is larger than the sum of its proper divisors (153466837).

639445025 is a wasteful number, since it uses less digits than its factorization.

639445025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25577811 (or 25577806 counting only the distinct ones).

The product of its (nonzero) digits is 129600, while the sum is 38.

The square root of 639445025 is about 25287.2502459243. The cubic root of 639445025 is about 861.5247086872.

The spelling of 639445025 in words is "six hundred thirty-nine million, four hundred forty-five thousand, twenty-five".