639599 has 2 divisors, whose sum is σ = 639600. Its totient is φ = 639598.

The previous prime is 639589. The next prime is 639601. The reversal of 639599 is 995936.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639599 is a prime.

Together with 639601, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639589) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319799 + 319800.

It is an arithmetic number, because the mean of its divisors is an integer number (319800).

2⁶³⁹⁵⁹⁹ is an apocalyptic number.

639599 is a deficient number, since it is larger than the sum of its proper divisors (1).

639599 is an equidigital number, since it uses as much as digits as its factorization.

639599 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 65610, while the sum is 41.

The square root of 639599 is about 799.7493357296. The cubic root of 639599 is about 86.1593853344.

The spelling of 639599 in words is "six hundred thirty-nine thousand, five hundred ninety-nine".