665686 has 16 divisors (see below), whose sum is σ = 1208736. Its totient is φ = 268416.

The previous prime is 665677. The next prime is 665713. The reversal of 665686 is 686566.

It is a congruent number.

It is an unprimeable number.

665686 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1161 + ... + 1636.

It is an arithmetic number, because the mean of its divisors is an integer number (75546).

2⁶⁶⁵⁶⁸⁶ is an apocalyptic number.

665686 is a deficient number, since it is larger than the sum of its proper divisors (543050).

665686 is a wasteful number, since it uses less digits than its factorization.

665686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2823.

The product of its digits is 51840, while the sum is 37.

The square root of 665686 is about 815.8958266838. The cubic root of 665686 is about 87.3151908911.

The spelling of 665686 in words is "six hundred sixty-five thousand, six hundred eighty-six".