639538825 has 6 divisors (see below), whose sum is σ = 793028174. Its totient is φ = 511631040.

The previous prime is 639538811. The next prime is 639538829. The reversal of 639538825 is 528835936.

It can be written as a sum of positive squares in 3 ways, for example, as 52881984 + 586656841 = 7272^2 + 24221^2 .

It is not a de Polignac number, because 639538825 - 2⁹ = 639538313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (639538829) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12790752 + ... + 12790801.

Almost surely, 2^639538825 is an apocalyptic number.

It is an amenable number.

639538825 is a deficient number, since it is larger than the sum of its proper divisors (153489349).

639538825 is a wasteful number, since it uses less digits than its factorization.

639538825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25581563 (or 25581558 counting only the distinct ones).

The product of its digits is 1555200, while the sum is 49.

The square root of 639538825 is about 25289.1048675116. The cubic root of 639538825 is about 861.5668322284.

The spelling of 639538825 in words is "six hundred thirty-nine million, five hundred thirty-eight thousand, eight hundred twenty-five".