21112111121 has 2 divisors, whose sum is σ = 21112111122. Its totient is φ = 21112111120.

The previous prime is 21112111081. The next prime is 21112111151. The reversal of 21112111121 is 12111121112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20489059600 + 623051521 = 143140^2 + 24961^2 .

It is a cyclic number.

It is not a de Polignac number, because 21112111121 - 2³⁰ = 20038369297 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21112111096 and 21112111105.

It is not a weakly prime, because it can be changed into another prime (21112111151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10556055560 + 10556055561.

It is an arithmetic number, because the mean of its divisors is an integer number (10556055561).

Almost surely, 2^21112111121 is an apocalyptic number.

It is an amenable number.

21112111121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21112111121 is an equidigital number, since it uses as much as digits as its factorization.

21112111121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8, while the sum is 14.

Adding to 21112111121 its reverse (12111121112), we get a palindrome (33223232233).

Subtracting from 21112111121 its reverse (12111121112), we obtain a palindrome (9000990009).

The spelling of 21112111121 in words is "twenty-one billion, one hundred twelve million, one hundred eleven thousand, one hundred twenty-one".