686540 has 12 divisors (see below), whose sum is σ = 1441776. Its totient is φ = 274608.

The previous prime is 686519. The next prime is 686551. The reversal of 686540 is 45686.

686540 = 111² + 112² + ... + 150².

It is an Ulam number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 686540.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17144 + ... + 17183.

It is an arithmetic number, because the mean of its divisors is an integer number (120148).

2⁶⁸⁶⁵⁴⁰ is an apocalyptic number.

It is an amenable number.

686540 is an abundant number, since it is smaller than the sum of its proper divisors (755236).

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

686540 is a wasteful number, since it uses less digits than its factorization.

686540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34336 (or 34334 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 29.

The square root of 686540 is about 828.5770935767. The cubic root of 686540 is about 88.2176088302.

The spelling of 686540 in words is "six hundred eighty-six thousand, five hundred forty".