668565866 has 4 divisors (see below), whose sum is σ = 1002848802. Its totient is φ = 334282932.

The previous prime is 668565857. The next prime is 668565889.

668565866 is nontrivially palindromic in base 10.

668565866 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 661569841 + 6996025 = 25721^2 + 2645^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 167141465 + ... + 167141468.

Almost surely, 2^668565866 is an apocalyptic number.

668565866 is a deficient number, since it is larger than the sum of its proper divisors (334282936).

668565866 is a wasteful number, since it uses less digits than its factorization.

668565866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 334282935.

The product of its digits is 12441600, while the sum is 56.

The square root of 668565866 is about 25856.6406557387. The cubic root of 668565866 is about 874.4092299568.

The spelling of 668565866 in words is "six hundred sixty-eight million, five hundred sixty-five thousand, eight hundred sixty-six".