667689 has 8 divisors (see below), whose sum is σ = 971232. Its totient is φ = 404640.

The previous prime is 667687. The next prime is 667691. The reversal of 667689 is 986766.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (667687) and next prime (667691).

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

It is not a de Polignac number, because 667689 - 2¹ = 667687 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 667689.

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

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, 10084 + ... + 10149.

It is an arithmetic number, because the mean of its divisors is an integer number (121404).

2⁶⁶⁷⁶⁸⁹ is an apocalyptic number.

It is an amenable number.

667689 is a deficient number, since it is larger than the sum of its proper divisors (303543).

667689 is a wasteful number, since it uses less digits than its factorization.

667689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20247.

The product of its digits is 108864, while the sum is 42.

The square root of 667689 is about 817.1223898536. The cubic root of 667689 is about 87.4026781886.

The spelling of 667689 in words is "six hundred sixty-seven thousand, six hundred eighty-nine".