686688 has 48 divisors (see below), whose sum is σ = 1886976. Its totient is φ = 218240.

The previous prime is 686687. The next prime is 686723. The reversal of 686688 is 886686.

It is a tau number, because it is divible by the number of its divisors (48).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (686687) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2053 + ... + 2363.

It is an arithmetic number, because the mean of its divisors is an integer number (39312).

2⁶⁸⁶⁶⁸⁸ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 686688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (943488).

686688 is an abundant number, since it is smaller than the sum of its proper divisors (1200288).

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

686688 is a wasteful number, since it uses less digits than its factorization.

686688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 347 (or 339 counting only the distinct ones).

The product of its digits is 110592, while the sum is 42.

The square root of 686688 is about 828.6663984982. Note that the first 3 decimals coincide. The cubic root of 686688 is about 88.2239475083.

The spelling of 686688 in words is "six hundred eighty-six thousand, six hundred eighty-eight".