686844 has 18 divisors (see below), whose sum is σ = 1736280. Its totient is φ = 228936.

The previous prime is 686843. The next prime is 686863. The reversal of 686844 is 448686.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 19079 = 686844 / (6 + 8 + 6 + 8 + 4 + 4).

It is a junction number, because it is equal to n+sod(n) for n = 686799 and 686808.

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 5 ways as a sum of consecutive naturals, for example, 9504 + ... + 9575.

It is an arithmetic number, because the mean of its divisors is an integer number (96460).

2⁶⁸⁶⁸⁴⁴ is an apocalyptic number.

It is an amenable number.

686844 is an abundant number, since it is smaller than the sum of its proper divisors (1049436).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

686844 is a wasteful number, since it uses less digits than its factorization.

686844 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19089 (or 19084 counting only the distinct ones).

The product of its digits is 36864, while the sum is 36.

The square root of 686844 is about 828.7605202952. The cubic root of 686844 is about 88.2306278317.

The spelling of 686844 in words is "six hundred eighty-six thousand, eight hundred forty-four".