639280639 has 2 divisors, whose sum is σ = 639280640. Its totient is φ = 639280638.

The previous prime is 639280627. The next prime is 639280679. The reversal of 639280639 is 936082936.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 639280639 - 2²⁵ = 605726207 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 (639280679) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319640319 + 319640320.

It is an arithmetic number, because the mean of its divisors is an integer number (319640320).

Almost surely, 2^639280639 is an apocalyptic number.

639280639 is a deficient number, since it is larger than the sum of its proper divisors (1).

639280639 is an equidigital number, since it uses as much as digits as its factorization.

639280639 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 419904, while the sum is 46.

The square root of 639280639 is about 25283.9996638190. Note that the first 3 decimals coincide. The cubic root of 639280639 is about 861.4508765708.

The spelling of 639280639 in words is "six hundred thirty-nine million, two hundred eighty thousand, six hundred thirty-nine".