21113440121 has 2 divisors, whose sum is σ = 21113440122. Its totient is φ = 21113440120.

The previous prime is 21113440043. The next prime is 21113440141. The reversal of 21113440121 is 12104431112.

It is an a-pointer prime, because the next prime (21113440141) can be obtained adding 21113440121 to its sum of digits (20).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11026050025 + 10087390096 = 105005^2 + 100436^2 .

It is a cyclic number.

It is not a de Polignac number, because 21113440121 - 2¹⁰ = 21113439097 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21113440093 and 21113440102.

It is not a weakly prime, because it can be changed into another prime (21113440141) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10556720060 + 10556720061.

It is an arithmetic number, because the mean of its divisors is an integer number (10556720061).

Almost surely, 2^21113440121 is an apocalyptic number.

It is an amenable number.

21113440121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21113440121 is an equidigital number, since it uses as much as digits as its factorization.

21113440121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 192, while the sum is 20.

Adding to 21113440121 its reverse (12104431112), we get a palindrome (33217871233).

Subtracting from 21113440121 its reverse (12104431112), we obtain a palindrome (9009009009).

The spelling of 21113440121 in words is "twenty-one billion, one hundred thirteen million, four hundred forty thousand, one hundred twenty-one".