21110111220221 has 2 divisors, whose sum is σ = 21110111220222. Its totient is φ = 21110111220220.

The previous prime is 21110111220203. The next prime is 21110111220251. The reversal of 21110111220221 is 12202211101112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20811570280900 + 298540939321 = 4561970^2 + 546389^2 .

It is a cyclic number.

It is not a de Polignac number, because 21110111220221 - 2¹⁴ = 21110111203837 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21110111220221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21110111220251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555055610110 + 10555055610111.

It is an arithmetic number, because the mean of its divisors is an integer number (10555055610111).

Almost surely, 2^{21110111220221} is an apocalyptic number.

It is an amenable number.

21110111220221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21110111220221 is an equidigital number, since it uses as much as digits as its factorization.

21110111220221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 21110111220221 its reverse (12202211101112), we get a palindrome (33312322321333).

The spelling of 21110111220221 in words is "twenty-one trillion, one hundred ten billion, one hundred eleven million, two hundred twenty thousand, two hundred twenty-one".