639504539 has 4 divisors (see below), whose sum is σ = 639594720. Its totient is φ = 639414360.

The previous prime is 639504533. The next prime is 639504587. The reversal of 639504539 is 935405936.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 639504539 - 2¹² = 639500443 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 639504539.

It is not an unprimeable number, because it can be changed into a prime (639504533) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33452 + ... + 48969.

It is an arithmetic number, because the mean of its divisors is an integer number (159898680).

Almost surely, 2^639504539 is an apocalyptic number.

639504539 is a deficient number, since it is larger than the sum of its proper divisors (90181).

639504539 is an equidigital number, since it uses as much as digits as its factorization.

639504539 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90180.

The product of its (nonzero) digits is 437400, while the sum is 44.

The square root of 639504539 is about 25288.4269775722. The cubic root of 639504539 is about 861.5514356086.

The spelling of 639504539 in words is "six hundred thirty-nine million, five hundred four thousand, five hundred thirty-nine".