21211112202221 has 2 divisors, whose sum is σ = 21211112202222. Its totient is φ = 21211112202220.

The previous prime is 21211112202209. The next prime is 21211112202223. The reversal of 21211112202221 is 12220221111212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18984660265321 + 2226451936900 = 4357139^2 + 1492130^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21211112202221 is a prime.

It is a super-2 number, since 2×21211112202221² (a number of 27 digits) contains 22 as substring.

Together with 21211112202223, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21211112202193 and 21211112202202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21211112202223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605556101110 + 10605556101111.

It is an arithmetic number, because the mean of its divisors is an integer number (10605556101111).

Almost surely, 2^{21211112202221} is an apocalyptic number.

It is an amenable number.

21211112202221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211112202221 is an equidigital number, since it uses as much as digits as its factorization.

21211112202221 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 20.

Adding to 21211112202221 its reverse (12220221111212), we get a palindrome (33431333313433).

The spelling of 21211112202221 in words is "twenty-one trillion, two hundred eleven billion, one hundred twelve million, two hundred two thousand, two hundred twenty-one".