686868 has 96 divisors (see below), whose sum is σ = 2145024. Its totient is φ = 165888.

The previous prime is 686863. The next prime is 686879. The reversal of 686868 is 868686.

686868 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is an Ulam number.

686868 is an undulating number in base 10.

686868 is a modest number, since divided by 6868 gives 68 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (686863) by changing a digit.

686868 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 18546 + ... + 18582.

It is an arithmetic number, because the mean of its divisors is an integer number (22344).

2⁶⁸⁶⁸⁶⁸ is an apocalyptic number.

686868 is a gapful number since it is divisible by the number (68) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 686868, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1072512).

686868 is an abundant number, since it is smaller than the sum of its proper divisors (1458156).

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

686868 is a wasteful number, since it uses less digits than its factorization.

686868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81 (or 79 counting only the distinct ones).

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

The square root of 686868 is about 828.7749996229. The cubic root of 686868 is about 88.2316554839.

The spelling of 686868 in words is "six hundred eighty-six thousand, eight hundred sixty-eight".