666161661 has 8 divisors (see below), whose sum is σ = 968962464. Its totient is φ = 403734320.

The previous prime is 666161623. The next prime is 666161669. The reversal of 666161661 is 166161666.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 666161661 - 2⁷ = 666161533 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666161669) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 10093326 + ... + 10093391.

It is an arithmetic number, because the mean of its divisors is an integer number (121120308).

Almost surely, 2^666161661 is an apocalyptic number.

It is an amenable number.

666161661 is a deficient number, since it is larger than the sum of its proper divisors (302800803).

666161661 is a wasteful number, since it uses less digits than its factorization.

666161661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20186731.

The product of its digits is 46656, while the sum is 39.

The square root of 666161661 is about 25810.1077293374. The cubic root of 666161661 is about 873.3598274729.

The spelling of 666161661 in words is "six hundred sixty-six million, one hundred sixty-one thousand, six hundred sixty-one".