639372817 has 2 divisors, whose sum is σ = 639372818. Its totient is φ = 639372816.

The previous prime is 639372803. The next prime is 639372823. The reversal of 639372817 is 718273936.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 632824336 + 6548481 = 25156^2 + 2559^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639372817 is a prime.

It is not a weakly prime, because it can be changed into another prime (639372827) 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, 319686408 + 319686409.

It is an arithmetic number, because the mean of its divisors is an integer number (319686409).

Almost surely, 2^639372817 is an apocalyptic number.

It is an amenable number.

639372817 is a deficient number, since it is larger than the sum of its proper divisors (1).

639372817 is an equidigital number, since it uses as much as digits as its factorization.

639372817 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 381024, while the sum is 46.

The square root of 639372817 is about 25285.8224505354. The cubic root of 639372817 is about 861.4922788376.

The spelling of 639372817 in words is "six hundred thirty-nine million, three hundred seventy-two thousand, eight hundred seventeen".