666879 has 4 divisors (see below), whose sum is σ = 889176. Its totient is φ = 444584.

The previous prime is 666871. The next prime is 666889. The reversal of 666879 is 978666.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 666879 - 2³ = 666871 is a prime.

It is a D-number.

666879 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 666879.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666871) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 111144 + ... + 111149.

It is an arithmetic number, because the mean of its divisors is an integer number (222294).

2⁶⁶⁶⁸⁷⁹ is an apocalyptic number.

666879 is a deficient number, since it is larger than the sum of its proper divisors (222297).

666879 is a wasteful number, since it uses less digits than its factorization.

666879 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222296.

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

The square root of 666879 is about 816.6265976565. The cubic root of 666879 is about 87.3673200018.

The spelling of 666879 in words is "six hundred sixty-six thousand, eight hundred seventy-nine".