666216706661 has 8 divisors (see below), whose sum is σ = 726795775200. Its totient is φ = 605639957040.

The previous prime is 666216706559. The next prime is 666216706691. The reversal of 666216706661 is 166607612666.

666216706661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 666216706661 - 2²⁶ = 666149597797 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666216706691) 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, 50810 + ... + 1155428.

It is an arithmetic number, because the mean of its divisors is an integer number (90849471900).

Almost surely, 2^666216706661 is an apocalyptic number.

It is an amenable number.

666216706661 is a deficient number, since it is larger than the sum of its proper divisors (60579068539).

666216706661 is a wasteful number, since it uses less digits than its factorization.

666216706661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1159459.

The product of its (nonzero) digits is 3919104, while the sum is 53.

The spelling of 666216706661 in words is "six hundred sixty-six billion, two hundred sixteen million, seven hundred six thousand, six hundred sixty-one".