11111221204121 has 2 divisors, whose sum is σ = 11111221204122. Its totient is φ = 11111221204120.

The previous prime is 11111221204081. The next prime is 11111221204123. The reversal of 11111221204121 is 12140212211111.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9271196778496 + 1840024425625 = 3044864^2 + 1356475^2 .

It is an emirp because it is prime and its reverse (12140212211111) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 11111221204121 - 2²² = 11111217009817 is a prime.

Together with 11111221204123, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 11111221204093 and 11111221204102.

It is not a weakly prime, because it can be changed into another prime (11111221204123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5555610602060 + 5555610602061.

It is an arithmetic number, because the mean of its divisors is an integer number (5555610602061).

Almost surely, 2^{11111221204121} is an apocalyptic number.

It is an amenable number.

11111221204121 is a deficient number, since it is larger than the sum of its proper divisors (1).

11111221204121 is an equidigital number, since it uses as much as digits as its factorization.

11111221204121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64, while the sum is 20.

Adding to 11111221204121 its reverse (12140212211111), we get a palindrome (23251433415232).

The spelling of 11111221204121 in words is "eleven trillion, one hundred eleven billion, two hundred twenty-one million, two hundred four thousand, one hundred twenty-one".