21110220221221 has 2 divisors, whose sum is σ = 21110220221222. Its totient is φ = 21110220221220.

The previous prime is 21110220221219. The next prime is 21110220221303. The reversal of 21110220221221 is 12212202201112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17678778888996 + 3431441332225 = 4204614^2 + 1852415^2 .

It is a cyclic number.

It is not a de Polignac number, because 21110220221221 - 2¹ = 21110220221219 is a prime.

Together with 21110220221219, 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 (21110230221221) 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, 10555110110610 + 10555110110611.

It is an arithmetic number, because the mean of its divisors is an integer number (10555110110611).

Almost surely, 2^{21110220221221} is an apocalyptic number.

It is an amenable number.

21110220221221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21110220221221 is an equidigital number, since it uses as much as digits as its factorization.

21110220221221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 21110220221221 its reverse (12212202201112), we get a palindrome (33322422422333).

The spelling of 21110220221221 in words is "twenty-one trillion, one hundred ten billion, two hundred twenty million, two hundred twenty-one thousand, two hundred twenty-one".