686624 has 24 divisors (see below), whose sum is σ = 1386000. Its totient is φ = 334656.

The previous prime is 686611. The next prime is 686639. The reversal of 686624 is 426686.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is an unprimeable number.

686624 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 3 ways as a sum of consecutive naturals, for example, 1127 + ... + 1625.

It is an arithmetic number, because the mean of its divisors is an integer number (57750).

2⁶⁸⁶⁶²⁴ 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 686624, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (693000).

686624 is an abundant number, since it is smaller than the sum of its proper divisors (699376).

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

686624 is a wasteful number, since it uses less digits than its factorization.

686624 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 552 (or 544 counting only the distinct ones).

The product of its digits is 13824, while the sum is 32.

The square root of 686624 is about 828.6277813349. The cubic root of 686624 is about 88.2212065701.

The spelling of 686624 in words is "six hundred eighty-six thousand, six hundred twenty-four".