666566566 has 16 divisors (see below), whose sum is σ = 1095171840. Its totient is φ = 302861440.

The previous prime is 666566497. The next prime is 666566567. The reversal of 666566566 is 665665666.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666566567) 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, 337030 + ... + 339001.

It is an arithmetic number, because the mean of its divisors is an integer number (68448240).

Almost surely, 2^666566566 is an apocalyptic number.

666566566 is a deficient number, since it is larger than the sum of its proper divisors (428605274).

666566566 is a wasteful number, since it uses less digits than its factorization.

666566566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 676079.

The product of its digits is 6998400, while the sum is 52.

The square root of 666566566 is about 25817.9504608712. The cubic root of 666566566 is about 873.5367395543.

The spelling of 666566566 in words is "six hundred sixty-six million, five hundred sixty-six thousand, five hundred sixty-six".