221111210212121 has 2 divisors, whose sum is σ = 221111210212122. Its totient is φ = 221111210212120.

The previous prime is 221111210212103. The next prime is 221111210212127. The reversal of 221111210212121 is 121212012111122.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 158687558265625 + 62423651946496 = 12597125^2 + 7900864^2 .

It is a cyclic number.

It is not a de Polignac number, because 221111210212121 - 2¹⁸ = 221111209949977 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 221111210212093 and 221111210212102.

It is not a weakly prime, because it can be changed into another prime (221111210212127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110555605106060 + 110555605106061.

It is an arithmetic number, because the mean of its divisors is an integer number (110555605106061).

Almost surely, 2^{221111210212121} is an apocalyptic number.

It is an amenable number.

221111210212121 is a deficient number, since it is larger than the sum of its proper divisors (1).

221111210212121 is an equidigital number, since it uses as much as digits as its factorization.

221111210212121 is an evil number, because the sum of its binary digits is even.

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

Adding to 221111210212121 its reverse (121212012111122), we get a palindrome (342323222323243).

The spelling of 221111210212121 in words is "two hundred twenty-one trillion, one hundred eleven billion, two hundred ten million, two hundred twelve thousand, one hundred twenty-one".