665997 has 4 divisors (see below), whose sum is σ = 888000. Its totient is φ = 443996.

The previous prime is 665993. The next prime is 666013. The reversal of 665997 is 799566.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 665997 - 2² = 665993 is a prime.

It is a D-number.

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 665997.

It is not an unprimeable number, because it can be changed into a prime (665993) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 110997 + ... + 111002.

It is an arithmetic number, because the mean of its divisors is an integer number (222000).

2⁶⁶⁵⁹⁹⁷ is an apocalyptic number.

It is an amenable number.

665997 is a deficient number, since it is larger than the sum of its proper divisors (222003).

665997 is a wasteful number, since it uses less digits than its factorization.

665997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222002.

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

The square root of 665997 is about 816.0863924855. The cubic root of 665997 is about 87.3287862883.

The spelling of 665997 in words is "six hundred sixty-five thousand, nine hundred ninety-seven".