13221211561 has 2 divisors, whose sum is σ = 13221211562. Its totient is φ = 13221211560.

The previous prime is 13221211481. The next prime is 13221211567. The reversal of 13221211561 is 16511212231.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8302854400 + 4918357161 = 91120^2 + 70131^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-13221211561 is a prime.

It is not a weakly prime, because it can be changed into another prime (13221211567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6610605780 + 6610605781.

It is an arithmetic number, because the mean of its divisors is an integer number (6610605781).

Almost surely, 2^13221211561 is an apocalyptic number.

It is an amenable number.

13221211561 is a deficient number, since it is larger than the sum of its proper divisors (1).

13221211561 is an equidigital number, since it uses as much as digits as its factorization.

13221211561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 720, while the sum is 25.

Adding to 13221211561 its reverse (16511212231), we get a palindrome (29732423792).

The spelling of 13221211561 in words is "thirteen billion, two hundred twenty-one million, two hundred eleven thousand, five hundred sixty-one".