12566332721 has 2 divisors, whose sum is σ = 12566332722. Its totient is φ = 12566332720.

The previous prime is 12566332711. The next prime is 12566332733. The reversal of 12566332721 is 12723366521.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7143630400 + 5422702321 = 84520^2 + 73639^2 .

It is a cyclic number.

It is not a de Polignac number, because 12566332721 - 2⁶ = 12566332657 is a prime.

It is not a weakly prime, because it can be changed into another prime (12566332711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6283166360 + 6283166361.

It is an arithmetic number, because the mean of its divisors is an integer number (6283166361).

Almost surely, 2^12566332721 is an apocalyptic number.

It is an amenable number.

12566332721 is a deficient number, since it is larger than the sum of its proper divisors (1).

12566332721 is an equidigital number, since it uses as much as digits as its factorization.

12566332721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 38.

The spelling of 12566332721 in words is "twelve billion, five hundred sixty-six million, three hundred thirty-two thousand, seven hundred twenty-one".