686684857 has 2 divisors, whose sum is σ = 686684858. Its totient is φ = 686684856.

The previous prime is 686684797. The next prime is 686684897. The reversal of 686684857 is 758486686.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 530334841 + 156350016 = 23029^2 + 12504^2 .

It is a cyclic number.

It is not a de Polignac number, because 686684857 - 2⁷ = 686684729 is a prime.

It is a super-2 number, since 2×686684857² = 943072185666220898, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (686684897) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343342428 + 343342429.

It is an arithmetic number, because the mean of its divisors is an integer number (343342429).

Almost surely, 2^686684857 is an apocalyptic number.

It is an amenable number.

686684857 is a deficient number, since it is larger than the sum of its proper divisors (1).

686684857 is an equidigital number, since it uses as much as digits as its factorization.

686684857 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15482880, while the sum is 58.

The square root of 686684857 is about 26204.6724268784. The cubic root of 686684857 is about 882.2381290648.

The spelling of 686684857 in words is "six hundred eighty-six million, six hundred eighty-four thousand, eight hundred fifty-seven".