668999 has 2 divisors, whose sum is σ = 669000. Its totient is φ = 668998.

The previous prime is 668989. The next prime is 669023. The reversal of 668999 is 999866.

It is a happy number.

668999 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-668999 is a prime.

668999 is a modest number, since divided by 999 gives 668 as remainder.

It is a plaindrome in base 10.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (668929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334499 + 334500.

It is an arithmetic number, because the mean of its divisors is an integer number (334500).

2⁶⁶⁸⁹⁹⁹ is an apocalyptic number.

668999 is a deficient number, since it is larger than the sum of its proper divisors (1).

668999 is an equidigital number, since it uses as much as digits as its factorization.

668999 is an evil number, because the sum of its binary digits is even.

The product of its digits is 209952, while the sum is 47.

The square root of 668999 is about 817.9235905633. The cubic root of 668999 is about 87.4598019437.

The spelling of 668999 in words is "six hundred sixty-eight thousand, nine hundred ninety-nine".