665958 has 16 divisors (see below), whose sum is σ = 1410480. Its totient is φ = 208896.

The previous prime is 665953. The next prime is 665981. The reversal of 665958 is 859566.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 665958.

It is not an unprimeable number, because it can be changed into a prime (665953) by changing a digit.

665958 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, 3163 + ... + 3366.

It is an arithmetic number, because the mean of its divisors is an integer number (88155).

2⁶⁶⁵⁹⁵⁸ is an apocalyptic number.

665958 is an abundant number, since it is smaller than the sum of its proper divisors (744522).

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

665958 is a wasteful number, since it uses less digits than its factorization.

665958 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6551.

The product of its digits is 64800, while the sum is 39.

The square root of 665958 is about 816.0624976066. The cubic root of 665958 is about 87.3270816314.

The spelling of 665958 in words is "six hundred sixty-five thousand, nine hundred fifty-eight".