687666 has 24 divisors (see below), whose sum is σ = 1600560. Its totient is φ = 196392.

The previous prime is 687647. The next prime is 687679. The reversal of 687666 is 666786.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 687666.

It is an unprimeable number.

687666 is an untouchable number, because it is not equal to the sum of proper divisors of any 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 11 ways as a sum of consecutive naturals, for example, 876 + ... + 1463.

It is an arithmetic number, because the mean of its divisors is an integer number (66690).

2⁶⁸⁷⁶⁶⁶ is an apocalyptic number.

687666 is an abundant number, since it is smaller than the sum of its proper divisors (912894).

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

687666 is a wasteful number, since it uses less digits than its factorization.

687666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2358 (or 2351 counting only the distinct ones).

The product of its digits is 72576, while the sum is 39.

The square root of 687666 is about 829.2562933135. The cubic root of 687666 is about 88.2658113003.

The spelling of 687666 in words is "six hundred eighty-seven thousand, six hundred sixty-six".