12216516721 has 4 divisors (see below), whose sum is σ = 12220526500. Its totient is φ = 12212506944.

The previous prime is 12216516709. The next prime is 12216516733. The reversal of 12216516721 is 12761561221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12761561221 = 67 ⋅190471063.

It is an interprime number because it is at equal distance from previous prime (12216516709) and next prime (12216516733).

It can be written as a sum of positive squares in 2 ways, for example, as 929579121 + 11286937600 = 30489^2 + 106240^2 .

It is a cyclic number.

It is not a de Polignac number, because 12216516721 - 2²⁷ = 12082298993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12216516701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2000316 + ... + 2006413.

It is an arithmetic number, because the mean of its divisors is an integer number (3055131625).

Almost surely, 2^12216516721 is an apocalyptic number.

It is an amenable number.

12216516721 is a deficient number, since it is larger than the sum of its proper divisors (4009779).

12216516721 is an equidigital number, since it uses as much as digits as its factorization.

12216516721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4009778.

The product of its digits is 10080, while the sum is 34.

The spelling of 12216516721 in words is "twelve billion, two hundred sixteen million, five hundred sixteen thousand, seven hundred twenty-one".