686637857 has 2 divisors, whose sum is σ = 686637858. Its totient is φ = 686637856.

The previous prime is 686637841. The next prime is 686637907. The reversal of 686637857 is 758736686.

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., 412536721 + 274101136 = 20311^2 + 16556^2 .

It is a cyclic number.

It is not a de Polignac number, because 686637857 - 2⁴ = 686637841 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (686657857) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343318928 + 343318929.

It is an arithmetic number, because the mean of its divisors is an integer number (343318929).

Almost surely, 2^686637857 is an apocalyptic number.

It is an amenable number.

686637857 is a deficient number, since it is larger than the sum of its proper divisors (1).

686637857 is an equidigital number, since it uses as much as digits as its factorization.

686637857 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10160640, while the sum is 56.

The square root of 686637857 is about 26203.7756248980. The cubic root of 686637857 is about 882.2180004048.

The spelling of 686637857 in words is "six hundred eighty-six million, six hundred thirty-seven thousand, eight hundred fifty-seven".