686669 has 2 divisors, whose sum is σ = 686670. Its totient is φ = 686668.

The previous prime is 686639. The next prime is 686671. The reversal of 686669 is 966686.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 405769 + 280900 = 637^2 + 530^2 .

It is a cyclic number.

It is not a de Polignac number, because 686669 - 2¹⁶ = 621133 is a prime.

It is a super-2 number, since 2×686669² = 943028631122, which contains 22 as substring.

Together with 686671, it forms a pair of twin primes.

It is a Chen prime.

It is a zygodrome in base 7.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (686639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343334 + 343335.

It is an arithmetic number, because the mean of its divisors is an integer number (343335).

2⁶⁸⁶⁶⁶⁹ is an apocalyptic number.

It is an amenable number.

686669 is a deficient number, since it is larger than the sum of its proper divisors (1).

686669 is an equidigital number, since it uses as much as digits as its factorization.

686669 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 93312, while the sum is 41.

The square root of 686669 is about 828.6549342157. The cubic root of 686669 is about 88.2231338100.

The spelling of 686669 in words is "six hundred eighty-six thousand, six hundred sixty-nine".