668999999 has 2 divisors, whose sum is σ = 669000000. Its totient is φ = 668999998.

The previous prime is 668999987. The next prime is 669000001. The reversal of 668999999 is 999999866.

It is a happy number.

668999999 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 668999999 - 2⁸ = 668999743 is a prime.

Together with 669000001, it forms a pair of twin primes.

It is a Chen prime.

668999999 is a modest number, since divided by 99999 gives 6689 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 (668999299) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334499999 + 334500000.

It is an arithmetic number, because the mean of its divisors is an integer number (334500000).

Almost surely, 2^668999999 is an apocalyptic number.

668999999 is a deficient number, since it is larger than the sum of its proper divisors (1).

668999999 is an equidigital number, since it uses as much as digits as its factorization.

668999999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 153055008, while the sum is 74.

The square root of 668999999 is about 25865.0342934240. The cubic root of 668999999 is about 874.5984547759.

The spelling of 668999999 in words is "six hundred sixty-eight million, nine hundred ninety-nine thousand, nine hundred ninety-nine".