1211122212221 has 2 divisors, whose sum is σ = 1211122212222. Its totient is φ = 1211122212220.

The previous prime is 1211122212199. The next prime is 1211122212233. The reversal of 1211122212221 is 1222122211121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 777086325625 + 434035886596 = 881525^2 + 658814^2 .

It is a cyclic number.

It is not a de Polignac number, because 1211122212221 - 2³⁴ = 1193942343037 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1211122212193 and 1211122212202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1211122212121) 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 as a sum of consecutive naturals, namely, 605561106110 + 605561106111.

It is an arithmetic number, because the mean of its divisors is an integer number (605561106111).

Almost surely, 2^{1211122212221} is an apocalyptic number.

It is an amenable number.

1211122212221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211122212221 is an equidigital number, since it uses as much as digits as its factorization.

1211122212221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 128, while the sum is 20.

Adding to 1211122212221 its reverse (1222122211121), we get a palindrome (2433244423342).

The spelling of 1211122212221 in words is "one trillion, two hundred eleven billion, one hundred twenty-two million, two hundred twelve thousand, two hundred twenty-one".