668557889 has 2 divisors, whose sum is σ = 668557890. Its totient is φ = 668557888.

The previous prime is 668557867. The next prime is 668557907. The reversal of 668557889 is 988755866.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 665227264 + 3330625 = 25792^2 + 1825^2 .

It is a cyclic number.

It is not a de Polignac number, because 668557889 - 2²⁰ = 667509313 is a prime.

It is not a weakly prime, because it can be changed into another prime (668557489) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334278944 + 334278945.

It is an arithmetic number, because the mean of its divisors is an integer number (334278945).

Almost surely, 2^668557889 is an apocalyptic number.

It is an amenable number.

668557889 is a deficient number, since it is larger than the sum of its proper divisors (1).

668557889 is an equidigital number, since it uses as much as digits as its factorization.

668557889 is an evil number, because the sum of its binary digits is even.

The product of its digits is 29030400, while the sum is 62.

The square root of 668557889 is about 25856.4864009014. The cubic root of 668557889 is about 874.4057522689.

The spelling of 668557889 in words is "six hundred sixty-eight million, five hundred fifty-seven thousand, eight hundred eighty-nine".