686686424681 has 2 divisors, whose sum is σ = 686686424682. Its totient is φ = 686686424680.

The previous prime is 686686424663. The next prime is 686686424719. The reversal of 686686424681 is 186424686686.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 618417096025 + 68269328656 = 786395^2 + 261284^2 .

It is a cyclic number.

It is not a de Polignac number, because 686686424681 - 2³⁸ = 411808517737 is a prime.

It is a super-2 number, since 2×686686424681² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (686686424651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343343212340 + 343343212341.

It is an arithmetic number, because the mean of its divisors is an integer number (343343212341).

Almost surely, 2^686686424681 is an apocalyptic number.

It is an amenable number.

686686424681 is a deficient number, since it is larger than the sum of its proper divisors (1).

686686424681 is an equidigital number, since it uses as much as digits as its factorization.

686686424681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 127401984, while the sum is 65.

The spelling of 686686424681 in words is "six hundred eighty-six billion, six hundred eighty-six million, four hundred twenty-four thousand, six hundred eighty-one".