21111122210221 has 2 divisors, whose sum is σ = 21111122210222. Its totient is φ = 21111122210220.

The previous prime is 21111122210219. The next prime is 21111122210231. The reversal of 21111122210221 is 12201222111112.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15806110976100 + 5305011234121 = 3975690^2 + 2303261^2 .

It is a cyclic number.

It is not a de Polignac number, because 21111122210221 - 2¹ = 21111122210219 is a prime.

Together with 21111122210219, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21111122210231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555561105110 + 10555561105111.

It is an arithmetic number, because the mean of its divisors is an integer number (10555561105111).

Almost surely, 2^{21111122210221} is an apocalyptic number.

It is an amenable number.

21111122210221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111122210221 is an equidigital number, since it uses as much as digits as its factorization.

21111122210221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64, while the sum is 19.

Adding to 21111122210221 its reverse (12201222111112), we get a palindrome (33312344321333).

The spelling of 21111122210221 in words is "twenty-one trillion, one hundred eleven billion, one hundred twenty-two million, two hundred ten thousand, two hundred twenty-one".