666626666 has 32 divisors (see below), whose sum is σ = 1104453120. Its totient is φ = 300542400.

The previous prime is 666626659. The next prime is 666626699.

666626666 is nontrivially palindromic in base 10.

It is a super-2 number, since 2×666626666² = 888782223644551112, which contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

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 in 15 ways as a sum of consecutive naturals, for example, 67220 + ... + 76496.

It is an arithmetic number, because the mean of its divisors is an integer number (34514160).

Almost surely, 2^666626666 is an apocalyptic number.

666626666 is a deficient number, since it is larger than the sum of its proper divisors (437826454).

666626666 is a wasteful number, since it uses less digits than its factorization.

666626666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9390.

The product of its digits is 3359232, while the sum is 50.

The square root of 666626666 is about 25819.1143535172. The cubic root of 666626666 is about 873.5629924864.

The spelling of 666626666 in words is "six hundred sixty-six million, six hundred twenty-six thousand, six hundred sixty-six".