12216661221 has 16 divisors (see below), whose sum is σ = 16964754048. Its totient is φ = 7812705600.

The previous prime is 12216661201. The next prime is 12216661229.

12216661221 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 12216661221 - 2⁵ = 12216661189 is a prime.

It is a super-2 number, since 2×12216661221² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12216661229) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 767190 + ... + 782951.

It is an arithmetic number, because the mean of its divisors is an integer number (1060297128).

Almost surely, 2^12216661221 is an apocalyptic number.

It is an amenable number.

12216661221 is a deficient number, since it is larger than the sum of its proper divisors (4748092827).

12216661221 is a wasteful number, since it uses less digits than its factorization.

12216661221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1550252.

The product of its digits is 3456, while the sum is 30.

The spelling of 12216661221 in words is "twelve billion, two hundred sixteen million, six hundred sixty-one thousand, two hundred twenty-one".