11111221210121 has 2 divisors, whose sum is σ = 11111221210122. Its totient is φ = 11111221210120.

The previous prime is 11111221210069. The next prime is 11111221210123. The reversal of 11111221210121 is 12101212211111.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7198816329721 + 3912404880400 = 2683061^2 + 1977980^2 .

It is a cyclic number.

It is not a de Polignac number, because 11111221210121 - 2¹⁰ = 11111221209097 is a prime.

Together with 11111221210123, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 11111221210121.

It is not a weakly prime, because it can be changed into another prime (11111221210123) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5555610605060 + 5555610605061.

It is an arithmetic number, because the mean of its divisors is an integer number (5555610605061).

Almost surely, 2^{11111221210121} is an apocalyptic number.

It is an amenable number.

11111221210121 is a deficient number, since it is larger than the sum of its proper divisors (1).

11111221210121 is an equidigital number, since it uses as much as digits as its factorization.

11111221210121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16, while the sum is 17.

Adding to 11111221210121 its reverse (12101212211111), we get a palindrome (23212433421232).

The spelling of 11111221210121 in words is "eleven trillion, one hundred eleven billion, two hundred twenty-one million, two hundred ten thousand, one hundred twenty-one".