639895679 has 2 divisors, whose sum is σ = 639895680. Its totient is φ = 639895678.

The previous prime is 639895667. The next prime is 639895709. The reversal of 639895679 is 976598936.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 639895679 - 2⁸ = 639895423 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639895579) 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, 319947839 + 319947840.

It is an arithmetic number, because the mean of its divisors is an integer number (319947840).

Almost surely, 2^639895679 is an apocalyptic number.

639895679 is a deficient number, since it is larger than the sum of its proper divisors (1).

639895679 is an equidigital number, since it uses as much as digits as its factorization.

639895679 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 22044960, while the sum is 62.

The square root of 639895679 is about 25296.1593725214. The cubic root of 639895679 is about 861.7270499723.

The spelling of 639895679 in words is "six hundred thirty-nine million, eight hundred ninety-five thousand, six hundred seventy-nine".