11111222111221 has 2 divisors, whose sum is σ = 11111222111222. Its totient is φ = 11111222111220.

The previous prime is 11111222111173. The next prime is 11111222111239. The reversal of 11111222111221 is 12211122211111.

11111222111221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9932021583121 + 1179200528100 = 3151511^2 + 1085910^2 .

It is a cyclic number.

It is not a de Polignac number, because 11111222111221 - 2²⁹ = 11110685240309 is a prime.

It is a super-2 number, since 2×11111222111221² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11111222111281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5555611055610 + 5555611055611.

It is an arithmetic number, because the mean of its divisors is an integer number (5555611055611).

Almost surely, 2^{11111222111221} is an apocalyptic number.

It is an amenable number.

11111222111221 is a deficient number, since it is larger than the sum of its proper divisors (1).

11111222111221 is an equidigital number, since it uses as much as digits as its factorization.

11111222111221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 32, while the sum is 19.

Adding to 11111222111221 its reverse (12211122211111), we get a palindrome (23322344322332).

The spelling of 11111222111221 in words is "eleven trillion, one hundred eleven billion, two hundred twenty-two million, one hundred eleven thousand, two hundred twenty-one".