667686 has 16 divisors (see below), whose sum is σ = 1343664. Its totient is φ = 221184.

The previous prime is 667673. The next prime is 667687. The reversal of 667686 is 686766.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (667687) by changing a digit.

667686 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 (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1326 + ... + 1758.

It is an arithmetic number, because the mean of its divisors is an integer number (83979).

2⁶⁶⁷⁶⁸⁶ is an apocalyptic number.

667686 is an abundant number, since it is smaller than the sum of its proper divisors (675978).

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

667686 is a wasteful number, since it uses less digits than its factorization.

667686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 695.

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

The square root of 667686 is about 817.1205541412. The cubic root of 667686 is about 87.4025472851.

The spelling of 667686 in words is "six hundred sixty-seven thousand, six hundred eighty-six".