21211100220221 has 2 divisors, whose sum is σ = 21211100220222. Its totient is φ = 21211100220220.

The previous prime is 21211100220199. The next prime is 21211100220287. The reversal of 21211100220221 is 12202200111212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20810575783321 + 400524436900 = 4561861^2 + 632870^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211100220221 - 2¹⁸ = 21211099958077 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21211100220221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21211100420221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605550110110 + 10605550110111.

It is an arithmetic number, because the mean of its divisors is an integer number (10605550110111).

Almost surely, 2^{21211100220221} is an apocalyptic number.

It is an amenable number.

21211100220221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211100220221 is an equidigital number, since it uses as much as digits as its factorization.

21211100220221 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 17.

Adding to 21211100220221 its reverse (12202200111212), we get a palindrome (33413300331433).

The spelling of 21211100220221 in words is "twenty-one trillion, two hundred eleven billion, one hundred million, two hundred twenty thousand, two hundred twenty-one".