686440 has 24 divisors (see below), whose sum is σ = 1556370. Its totient is φ = 272480.

The previous prime is 686437. The next prime is 686449. The reversal of 686440 is 44686.

686440 is nontrivially palindromic in base 3.

686440 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 617796 + 68644 = 786^2 + 262^2 .

It is a junction number, because it is equal to n+sod(n) for n = 686399 and 686408.

It is not an unprimeable number, because it can be changed into a prime (686449) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 5175 + ... + 5305.

2⁶⁸⁶⁴⁴⁰ is an apocalyptic number.

It is an amenable number.

686440 is an abundant number, since it is smaller than the sum of its proper divisors (869930).

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

686440 is a wasteful number, since it uses less digits than its factorization.

686440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 273 (or 138 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 28.

The square root of 686440 is about 828.5167469641. The cubic root of 686440 is about 88.2133254240.

The spelling of 686440 in words is "six hundred eighty-six thousand, four hundred forty".