686628 has 18 divisors (see below), whose sum is σ = 1735734. Its totient is φ = 228864.

The previous prime is 686611. The next prime is 686639. The reversal of 686628 is 826686.

686628 is nontrivially palindromic in base 7.

It can be written as a sum of positive squares in only one way, i.e., 381924 + 304704 = 618^2 + 552^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 19073 = 686628 / (6 + 8 + 6 + 6 + 2 + 8).

It is a junction number, because it is equal to n+sod(n) for n = 686592 and 686601.

It is an unprimeable number.

686628 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 5 ways as a sum of consecutive naturals, for example, 9501 + ... + 9572.

2⁶⁸⁶⁶²⁸ is an apocalyptic number.

It is an amenable number.

686628 is an abundant number, since it is smaller than the sum of its proper divisors (1049106).

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

686628 is a wasteful number, since it uses less digits than its factorization.

686628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19083 (or 19078 counting only the distinct ones).

The product of its digits is 27648, while the sum is 36.

The square root of 686628 is about 828.6301949603. The cubic root of 686628 is about 88.2213778837.

The spelling of 686628 in words is "six hundred eighty-six thousand, six hundred twenty-eight".