665979 has 8 divisors (see below), whose sum is σ = 900432. Its totient is φ = 437760.

The previous prime is 665953. The next prime is 665981. The reversal of 665979 is 979566.

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

It is not a de Polignac number, because 665979 - 2⁵ = 665947 is a prime.

It is an Ulam number.

It is a plaindrome in base 14.

It is a self number, because there is not a number n which added to its sum of digits gives 665979.

It is not an unprimeable number, because it can be changed into a prime (665179) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1302 + ... + 1739.

It is an arithmetic number, because the mean of its divisors is an integer number (112554).

2⁶⁶⁵⁹⁷⁹ is an apocalyptic number.

665979 is a deficient number, since it is larger than the sum of its proper divisors (234453).

665979 is a wasteful number, since it uses less digits than its factorization.

665979 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3117.

The product of its digits is 102060, while the sum is 42.

The square root of 665979 is about 816.0753641668. The cubic root of 665979 is about 87.3279995318.

The spelling of 665979 in words is "six hundred sixty-five thousand, nine hundred seventy-nine".