639857758909 has 2 divisors, whose sum is σ = 639857758910. Its totient is φ = 639857758908.

The previous prime is 639857758889. The next prime is 639857758979. The reversal of 639857758909 is 909857758936.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 432072211684 + 207785547225 = 657322^2 + 455835^2 .

It is a cyclic number.

It is not a de Polignac number, because 639857758909 - 2²⁷ = 639723541181 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639857758979) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319928879454 + 319928879455.

It is an arithmetic number, because the mean of its divisors is an integer number (319928879455).

Almost surely, 2^639857758909 is an apocalyptic number.

It is an amenable number.

639857758909 is a deficient number, since it is larger than the sum of its proper divisors (1).

639857758909 is an equidigital number, since it uses as much as digits as its factorization.

639857758909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1028764800, while the sum is 76.

The spelling of 639857758909 in words is "six hundred thirty-nine billion, eight hundred fifty-seven million, seven hundred fifty-eight thousand, nine hundred nine".