666646666 has 24 divisors (see below), whose sum is σ = 1164126276. Its totient is φ = 285485760.

The previous prime is 666646627. The next prime is 666646679.

666646666 is nontrivially palindromic in base 10.

666646666 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 612315025 + 54331641 = 24745^2 + 7371^2 .

It is a Smith number, since the sum of its digits (52) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 231910 + ... + 234766.

Almost surely, 2^666646666 is an apocalyptic number.

666646666 is a deficient number, since it is larger than the sum of its proper divisors (497479610).

666646666 is a wasteful number, since it uses less digits than its factorization.

666646666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5254 (or 5247 counting only the distinct ones).

The product of its digits is 6718464, while the sum is 52.

The square root of 666646666 is about 25819.5016605666. The cubic root of 666646666 is about 873.5717285531.

The spelling of 666646666 in words is "six hundred sixty-six million, six hundred forty-six thousand, six hundred sixty-six".