639959839 has 2 divisors, whose sum is σ = 639959840. Its totient is φ = 639959838.

The previous prime is 639959783. The next prime is 639959863. The reversal of 639959839 is 938959936.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 639959839 - 2¹³ = 639951647 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639959869) 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 as a sum of consecutive naturals, namely, 319979919 + 319979920.

It is an arithmetic number, because the mean of its divisors is an integer number (319979920).

Almost surely, 2^639959839 is an apocalyptic number.

639959839 is a deficient number, since it is larger than the sum of its proper divisors (1).

639959839 is an equidigital number, since it uses as much as digits as its factorization.

639959839 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14171760, while the sum is 61.

The square root of 639959839 is about 25297.4275174374. The cubic root of 639959839 is about 861.7558497499.

The spelling of 639959839 in words is "six hundred thirty-nine million, nine hundred fifty-nine thousand, eight hundred thirty-nine".