666505666 has 16 divisors (see below), whose sum is σ = 1044482040. Its totient is φ = 318572800.

The previous prime is 666505657. The next prime is 666505667.

666505666 is nontrivially palindromic in base 10.

It can be written as a sum of positive squares in 4 ways, for example, as 529966441 + 136539225 = 23021^2 + 11685^2 .

It is not an unprimeable number, because it can be changed into a prime (666505667) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 51031 + ... + 62746.

Almost surely, 2^666505666 is an apocalyptic number.

666505666 is a deficient number, since it is larger than the sum of its proper divisors (377976374).

666505666 is a wasteful number, since it uses less digits than its factorization.

666505666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 113909.

The product of its (nonzero) digits is 1166400, while the sum is 46.

The square root of 666505666 is about 25816.7710219539. The cubic root of 666505666 is about 873.5101355559.

The spelling of 666505666 in words is "six hundred sixty-six million, five hundred five thousand, six hundred sixty-six".