21201122111111 has 2 divisors, whose sum is σ = 21201122111112. Its totient is φ = 21201122111110.

The previous prime is 21201122111051. The next prime is 21201122111149. The reversal of 21201122111111 is 11111122110212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21201122111111 - 2¹⁸ = 21201121848967 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21201122111111.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21201122111161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600561055555 + 10600561055556.

It is an arithmetic number, because the mean of its divisors is an integer number (10600561055556).

Almost surely, 2^{21201122111111} is an apocalyptic number.

21201122111111 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201122111111 is an equidigital number, since it uses as much as digits as its factorization.

21201122111111 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 21201122111111 its reverse (11111122110212), we get a palindrome (32312244221323).

The spelling of 21201122111111 in words is "twenty-one trillion, two hundred one billion, one hundred twenty-two million, one hundred eleven thousand, one hundred eleven".