639813859 has 2 divisors, whose sum is σ = 639813860. Its totient is φ = 639813858.

The previous prime is 639813851. The next prime is 639813869. The reversal of 639813859 is 958318936.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 639813859 - 2³ = 639813851 is a prime.

It is not a weakly prime, because it can be changed into another prime (639813851) 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, 319906929 + 319906930.

It is an arithmetic number, because the mean of its divisors is an integer number (319906930).

Almost surely, 2^639813859 is an apocalyptic number.

639813859 is a deficient number, since it is larger than the sum of its proper divisors (1).

639813859 is an equidigital number, since it uses as much as digits as its factorization.

639813859 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1399680, while the sum is 52.

The square root of 639813859 is about 25294.5420792708. The cubic root of 639813859 is about 861.6903202809.

The spelling of 639813859 in words is "six hundred thirty-nine million, eight hundred thirteen thousand, eight hundred fifty-nine".