21211202202221 has 2 divisors, whose sum is σ = 21211202202222. Its totient is φ = 21211202202220.

The previous prime is 21211202202199. The next prime is 21211202202241. The reversal of 21211202202221 is 12220220211212.

It is an a-pointer prime, because the next prime (21211202202241) can be obtained adding 21211202202221 to its sum of digits (20).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13404129157225 + 7807073044996 = 3661165^2 + 2794114^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21211202202221 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21211202202193 and 21211202202202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21211202202241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605601101110 + 10605601101111.

It is an arithmetic number, because the mean of its divisors is an integer number (10605601101111).

Almost surely, 2^{21211202202221} is an apocalyptic number.

It is an amenable number.

21211202202221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211202202221 is an equidigital number, since it uses as much as digits as its factorization.

21211202202221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 256, while the sum is 20.

Adding to 21211202202221 its reverse (12220220211212), we get a palindrome (33431422413433).

The spelling of 21211202202221 in words is "twenty-one trillion, two hundred eleven billion, two hundred two million, two hundred two thousand, two hundred twenty-one".