688864 has 48 divisors (see below), whose sum is σ = 1572480. Its totient is φ = 293760.

The previous prime is 688861. The next prime is 688867. The reversal of 688864 is 468886.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (688861) and next prime (688867).

It is a super-2 number, since 2×688864² = 949067220992, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6637 + ... + 6739.

It is an arithmetic number, because the mean of its divisors is an integer number (32760).

2⁶⁸⁸⁸⁶⁴ 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 688864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (786240).

688864 is an abundant number, since it is smaller than the sum of its proper divisors (883616).

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

688864 is a wasteful number, since it uses less digits than its factorization.

688864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143 (or 135 counting only the distinct ones).

The product of its digits is 73728, while the sum is 40.

The square root of 688864 is about 829.9783129697. The cubic root of 688864 is about 88.3170382505.

The spelling of 688864 in words is "six hundred eighty-eight thousand, eight hundred sixty-four".