639979642171 has 2 divisors, whose sum is σ = 639979642172. Its totient is φ = 639979642170.

The previous prime is 639979642163. The next prime is 639979642177. The reversal of 639979642171 is 171246979936.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 639979642171 - 2³ = 639979642163 is a prime.

It is not a weakly prime, because it can be changed into another prime (639979642177) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319989821085 + 319989821086.

It is an arithmetic number, because the mean of its divisors is an integer number (319989821086).

Almost surely, 2^639979642171 is an apocalyptic number.

639979642171 is a deficient number, since it is larger than the sum of its proper divisors (1).

639979642171 is an equidigital number, since it uses as much as digits as its factorization.

639979642171 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30862944, while the sum is 64.

The spelling of 639979642171 in words is "six hundred thirty-nine billion, nine hundred seventy-nine million, six hundred forty-two thousand, one hundred seventy-one".