639823417 has 2 divisors, whose sum is σ = 639823418. Its totient is φ = 639823416.

The previous prime is 639823399. The next prime is 639823421. The reversal of 639823417 is 714328936.

639823417 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 638017081 + 1806336 = 25259^2 + 1344^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639823417 is a prime.

It is not a weakly prime, because it can be changed into another prime (639823427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319911708 + 319911709.

It is an arithmetic number, because the mean of its divisors is an integer number (319911709).

Almost surely, 2^639823417 is an apocalyptic number.

It is an amenable number.

639823417 is a deficient number, since it is larger than the sum of its proper divisors (1).

639823417 is an equidigital number, since it uses as much as digits as its factorization.

639823417 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 217728, while the sum is 43.

The square root of 639823417 is about 25294.7310126042. The cubic root of 639823417 is about 861.6946111096.

The spelling of 639823417 in words is "six hundred thirty-nine million, eight hundred twenty-three thousand, four hundred seventeen".