666686 has 8 divisors (see below), whose sum is σ = 1032384. Its totient is φ = 322560.

The previous prime is 666683. The next prime is 666697. The reversal of 666686 is 686666.

666686 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666683) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5315 + ... + 5438.

It is an arithmetic number, because the mean of its divisors is an integer number (129048).

2⁶⁶⁶⁶⁸⁶ is an apocalyptic number.

666686 is a deficient number, since it is larger than the sum of its proper divisors (365698).

666686 is a wasteful number, since it uses less digits than its factorization.

666686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10786.

The product of its digits is 62208, while the sum is 38.

The square root of 666686 is about 816.5084200423. The cubic root of 666686 is about 87.3588909266.

The spelling of 666686 in words is "six hundred sixty-six thousand, six hundred eighty-six".