686656 has 14 divisors (see below), whose sum is σ = 1362710. Its totient is φ = 343296.

The previous prime is 686639. The next prime is 686669. The reversal of 686656 is 656686.

It can be written as a sum of positive squares in only one way, i.e., 640000 + 46656 = 800^2 + 216^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5301 + ... + 5428.

2⁶⁸⁶⁶⁵⁶ is an apocalyptic number.

It is an amenable number.

686656 is a deficient number, since it is larger than the sum of its proper divisors (676054).

686656 is a wasteful number, since it uses less digits than its factorization.

686656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10741 (or 10731 counting only the distinct ones).

The product of its digits is 51840, while the sum is 37.

The square root of 686656 is about 828.6470901415. The cubic root of 686656 is about 88.2225770605. Note that the first 3 decimals are identical.

It can be divided in two parts, 68 and 6656, that added together give a square (6724 = 82²).

The spelling of 686656 in words is "six hundred eighty-six thousand, six hundred fifty-six".