666656111651 has 4 divisors (see below), whose sum is σ = 666659618400. Its totient is φ = 666652604904.

The previous prime is 666656111617. The next prime is 666656111677. The reversal of 666656111651 is 156111656666.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 666656111651 - 2³⁰ = 665582369827 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 666656111651.

It is not an unprimeable number, because it can be changed into a prime (666656111551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1450811 + ... + 1854228.

It is an arithmetic number, because the mean of its divisors is an integer number (166664904600).

Almost surely, 2^666656111651 is an apocalyptic number.

666656111651 is a deficient number, since it is larger than the sum of its proper divisors (3506749).

666656111651 is a wasteful number, since it uses less digits than its factorization.

666656111651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3506748.

The product of its digits is 1166400, while the sum is 50.

The spelling of 666656111651 in words is "six hundred sixty-six billion, six hundred fifty-six million, one hundred eleven thousand, six hundred fifty-one".