686813 has 4 divisors (see below), whose sum is σ = 694620. Its totient is φ = 679008.

The previous prime is 686801. The next prime is 686837. The reversal of 686813 is 318686.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 228484 + 458329 = 478^2 + 677^2 .

It is a cyclic number.

It is not a de Polignac number, because 686813 - 2⁴ = 686797 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 686813.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (686843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3770 + ... + 3947.

It is an arithmetic number, because the mean of its divisors is an integer number (173655).

2⁶⁸⁶⁸¹³ is an apocalyptic number.

It is an amenable number.

686813 is a deficient number, since it is larger than the sum of its proper divisors (7807).

686813 is an equidigital number, since it uses as much as digits as its factorization.

686813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7806.

The product of its digits is 6912, while the sum is 32.

The square root of 686813 is about 828.7418174558. The cubic root of 686813 is about 88.2293004120.

The spelling of 686813 in words is "six hundred eighty-six thousand, eight hundred thirteen".