686666671 has 2 divisors, whose sum is σ = 686666672. Its totient is φ = 686666670.

The previous prime is 686666641. The next prime is 686666711. The reversal of 686666671 is 176666686.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 686666671 - 2⁵ = 686666639 is a prime.

It is a super-2 number, since 2×686666671² = 943022234124444482, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (686666621) 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, 343333335 + 343333336.

It is an arithmetic number, because the mean of its divisors is an integer number (343333336).

Almost surely, 2^686666671 is an apocalyptic number.

686666671 is a deficient number, since it is larger than the sum of its proper divisors (1).

686666671 is an equidigital number, since it uses as much as digits as its factorization.

686666671 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2612736, while the sum is 52.

The square root of 686666671 is about 26204.3254253949. The cubic root of 686666671 is about 882.2303406671.

It can be divided in two parts, 6866 and 66671, that added together give a palindrome (73537).

The spelling of 686666671 in words is "six hundred eighty-six million, six hundred sixty-six thousand, six hundred seventy-one".