666997 has 4 divisors (see below), whose sum is σ = 675520. Its totient is φ = 658476.

The previous prime is 666989. The next prime is 667013. The reversal of 666997 is 799666.

It is a happy number.

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 666997 - 2³ = 666989 is a prime.

It is a Duffinian number.

666997 is a lucky 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 666997.

It is not an unprimeable number, because it can be changed into a prime (666937) 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 3 ways as a sum of consecutive naturals, for example, 4143 + ... + 4300.

It is an arithmetic number, because the mean of its divisors is an integer number (168880).

2⁶⁶⁶⁹⁹⁷ is an apocalyptic number.

It is an amenable number.

666997 is a deficient number, since it is larger than the sum of its proper divisors (8523).

666997 is an equidigital number, since it uses as much as digits as its factorization.

666997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8522.

The product of its digits is 122472, while the sum is 43.

The square root of 666997 is about 816.6988429036. The cubic root of 666997 is about 87.3724727285.

The spelling of 666997 in words is "six hundred sixty-six thousand, nine hundred ninety-seven".