666799 has 4 divisors (see below), whose sum is σ = 762064. Its totient is φ = 571536.

The previous prime is 666773. The next prime is 666811. The reversal of 666799 is 997666.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 997666 = 2 ⋅498833.

It is not a de Polignac number, because 666799 - 2⁷ = 666671 is a prime.

It is a Duffinian number.

It is a plaindrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666749) 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, 47622 + ... + 47635.

It is an arithmetic number, because the mean of its divisors is an integer number (190516).

2⁶⁶⁶⁷⁹⁹ is an apocalyptic number.

666799 is a deficient number, since it is larger than the sum of its proper divisors (95265).

666799 is an equidigital number, since it uses as much as digits as its factorization.

666799 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95264.

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

The square root of 666799 is about 816.5776141923. The cubic root of 666799 is about 87.3638262820.

The spelling of 666799 in words is "six hundred sixty-six thousand, seven hundred ninety-nine".