1666166566 has 16 divisors (see below), whose sum is σ = 2689649280. Its totient is φ = 771223680.

The previous prime is 1666166561. The next prime is 1666166587. The reversal of 1666166566 is 6656616661.

It is a super-2 number, since 2×1666166566² = 5552222051312464712, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666166561) 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, 399606 + ... + 403753.

It is an arithmetic number, because the mean of its divisors is an integer number (168103080).

Almost surely, 2^1666166566 is an apocalyptic number.

1666166566 is a deficient number, since it is larger than the sum of its proper divisors (1023482714).

1666166566 is a wasteful number, since it uses less digits than its factorization.

1666166566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 803439.

The product of its digits is 1399680, while the sum is 49.

The square root of 1666166566 is about 40818.7036295863. The cubic root of 1666166566 is about 1185.5125026528.

The spelling of 1666166566 in words is "one billion, six hundred sixty-six million, one hundred sixty-six thousand, five hundred sixty-six".