21110110111021 has 2 divisors, whose sum is σ = 21110110111022. Its totient is φ = 21110110111020.

The previous prime is 21110110110917. The next prime is 21110110111033. The reversal of 21110110111021 is 12011101101112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21101721382921 + 8388728100 = 4593661^2 + 91590^2 .

It is a cyclic number.

It is not a de Polignac number, because 21110110111021 - 2²⁵ = 21110076556589 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21110110110992 and 21110110111010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21110110111921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555055055510 + 10555055055511.

It is an arithmetic number, because the mean of its divisors is an integer number (10555055055511).

Almost surely, 2^{21110110111021} is an apocalyptic number.

It is an amenable number.

21110110111021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21110110111021 is an equidigital number, since it uses as much as digits as its factorization.

21110110111021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4, while the sum is 13.

Adding to 21110110111021 its reverse (12011101101112), we get a palindrome (33121211212133).

Subtracting from 21110110111021 its reverse (12011101101112), we obtain a palindrome (9099009009909).

The spelling of 21110110111021 in words is "twenty-one trillion, one hundred ten billion, one hundred ten million, one hundred eleven thousand, twenty-one".