686999 has 6 divisors (see below), whose sum is σ = 704184. Its totient is φ = 670220.

The previous prime is 686993. The next prime is 687007. The reversal of 686999 is 999686.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-686999 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (47).

It is a Duffinian number.

686999 is a modest number, since divided by 999 gives 686 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (686993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2054 + ... + 2364.

It is an arithmetic number, because the mean of its divisors is an integer number (117364).

2⁶⁸⁶⁹⁹⁹ is an apocalyptic number.

686999 is a deficient number, since it is larger than the sum of its proper divisors (17185).

686999 is an equidigital number, since it uses as much as digits as its factorization.

686999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 405 (or 358 counting only the distinct ones).

The product of its digits is 209952, while the sum is 47.

The square root of 686999 is about 828.8540281618. The cubic root of 686999 is about 88.2372643307.

The spelling of 686999 in words is "six hundred eighty-six thousand, nine hundred ninety-nine".