639938539 has 2 divisors, whose sum is σ = 639938540. Its totient is φ = 639938538.

The previous prime is 639938527. The next prime is 639938567. The reversal of 639938539 is 935839936.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 639938539 - 2⁹ = 639938027 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 639938539.

It is not a weakly prime, because it can be changed into another prime (639938339) by changing a digit.

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 as a sum of consecutive naturals, namely, 319969269 + 319969270.

It is an arithmetic number, because the mean of its divisors is an integer number (319969270).

Almost surely, 2^639938539 is an apocalyptic number.

639938539 is a deficient number, since it is larger than the sum of its proper divisors (1).

639938539 is an equidigital number, since it uses as much as digits as its factorization.

639938539 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4723920, while the sum is 55.

The square root of 639938539 is about 25297.0065225117. The cubic root of 639938539 is about 861.7462889400.

The spelling of 639938539 in words is "six hundred thirty-nine million, nine hundred thirty-eight thousand, five hundred thirty-nine".