686824 has 8 divisors (see below), whose sum is σ = 1287810. Its totient is φ = 343408.

The previous prime is 686801. The next prime is 686837. The reversal of 686824 is 428686.

It can be written as a sum of positive squares in only one way, i.e., 348100 + 338724 = 590^2 + 582^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 686824.

It is an unprimeable number.

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, 42919 + ... + 42934.

2⁶⁸⁶⁸²⁴ is an apocalyptic number.

It is an amenable number.

686824 is a deficient number, since it is larger than the sum of its proper divisors (600986).

686824 is a wasteful number, since it uses less digits than its factorization.

686824 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85859 (or 85855 counting only the distinct ones).

The product of its digits is 18432, while the sum is 34.

The square root of 686824 is about 828.7484539955. The cubic root of 686824 is about 88.2297714365.

It can be divided in two parts, 68682 and 4, that added together give a palindrome (68686).

The spelling of 686824 in words is "six hundred eighty-six thousand, eight hundred twenty-four".