686681 has 8 divisors (see below), whose sum is σ = 751104. Its totient is φ = 624960.

The previous prime is 686671. The next prime is 686687. The reversal of 686681 is 186686.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 686681 - 2¹⁴ = 670297 is a prime.

It is a super-2 number, since 2×686681² = 943061591522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 686681.

It is not an unprimeable number, because it can be changed into a prime (686687) by changing a digit.

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

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 125 + ... + 1178.

It is an arithmetic number, because the mean of its divisors is an integer number (93888).

2⁶⁸⁶⁶⁸¹ is an apocalyptic number.

It is an amenable number.

686681 is a deficient number, since it is larger than the sum of its proper divisors (64423).

686681 is a wasteful number, since it uses less digits than its factorization.

686681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1351.

The product of its digits is 13824, while the sum is 35.

The square root of 686681 is about 828.6621748336. The cubic root of 686681 is about 88.2236477264.

The spelling of 686681 in words is "six hundred eighty-six thousand, six hundred eighty-one".