668818889 has 2 divisors, whose sum is σ = 668818890. Its totient is φ = 668818888.

The previous prime is 668818837. The next prime is 668818903. The reversal of 668818889 is 988818866.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 586608400 + 82210489 = 24220^2 + 9067^2 .

It is a cyclic number.

It is not a de Polignac number, because 668818889 - 2²⁸ = 400383433 is a prime.

It is not a weakly prime, because it can be changed into another prime (668818489) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334409444 + 334409445.

It is an arithmetic number, because the mean of its divisors is an integer number (334409445).

Almost surely, 2^668818889 is an apocalyptic number.

It is an amenable number.

668818889 is a deficient number, since it is larger than the sum of its proper divisors (1).

668818889 is an equidigital number, since it uses as much as digits as its factorization.

668818889 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10616832, while the sum is 62.

The square root of 668818889 is about 25861.5329978716. The cubic root of 668818889 is about 874.5195246204.

The spelling of 668818889 in words is "six hundred sixty-eight million, eight hundred eighteen thousand, eight hundred eighty-nine".