639913969 has 2 divisors, whose sum is σ = 639913970. Its totient is φ = 639913968.

The previous prime is 639913961. The next prime is 639913993. The reversal of 639913969 is 969319936.

639913969 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 326163600 + 313750369 = 18060^2 + 17713^2 .

It is a cyclic number.

It is not a de Polignac number, because 639913969 - 2³ = 639913961 is a prime.

It is a super-2 number, since 2×639913969² = 818979775442665922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (639913961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319956984 + 319956985.

It is an arithmetic number, because the mean of its divisors is an integer number (319956985).

Almost surely, 2^639913969 is an apocalyptic number.

It is an amenable number.

639913969 is a deficient number, since it is larger than the sum of its proper divisors (1).

639913969 is an equidigital number, since it uses as much as digits as its factorization.

639913969 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2125764, while the sum is 55.

The square root of 639913969 is about 25296.5208872683. The cubic root of 639913969 is about 861.7352600802.

The spelling of 639913969 in words is "six hundred thirty-nine million, nine hundred thirteen thousand, nine hundred sixty-nine".