686731 has 2 divisors, whose sum is σ = 686732. Its totient is φ = 686730.

The previous prime is 686729. The next prime is 686737. The reversal of 686731 is 137686.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 686731 - 2¹ = 686729 is a prime.

It is a super-2 number, since 2×686731² = 943198932722, which contains 22 as substring.

Together with 686729, it forms a pair of twin primes.

It is a Chen prime.

It is a nialpdrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 686693 and 686702.

It is not a weakly prime, because it can be changed into another prime (686737) 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 as a sum of consecutive naturals, namely, 343365 + 343366.

It is an arithmetic number, because the mean of its divisors is an integer number (343366).

2⁶⁸⁶⁷³¹ is an apocalyptic number.

686731 is a deficient number, since it is larger than the sum of its proper divisors (1).

686731 is an equidigital number, since it uses as much as digits as its factorization.

686731 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6048, while the sum is 31.

The square root of 686731 is about 828.6923433941. The cubic root of 686731 is about 88.2257889805.

The spelling of 686731 in words is "six hundred eighty-six thousand, seven hundred thirty-one".