686864665931 has 2 divisors, whose sum is σ = 686864665932. Its totient is φ = 686864665930.

The previous prime is 686864665919. The next prime is 686864665933. The reversal of 686864665931 is 139566468686.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 686864665931 - 2¹⁸ = 686864403787 is a prime.

It is a super-2 number, since 2×686864665931² (a number of 24 digits) contains 22 as substring.

Together with 686864665933, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (686864665933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343432332965 + 343432332966.

It is an arithmetic number, because the mean of its divisors is an integer number (343432332966).

Almost surely, 2^686864665931 is an apocalyptic number.

686864665931 is a deficient number, since it is larger than the sum of its proper divisors (1).

686864665931 is an equidigital number, since it uses as much as digits as its factorization.

686864665931 is an evil number, because the sum of its binary digits is even.

The product of its digits is 268738560, while the sum is 68.

The spelling of 686864665931 in words is "six hundred eighty-six billion, eight hundred sixty-four million, six hundred sixty-five thousand, nine hundred thirty-one".