21211021212221 has 2 divisors, whose sum is σ = 21211021212222. Its totient is φ = 21211021212220.

The previous prime is 21211021212203. The next prime is 21211021212233. The reversal of 21211021212221 is 12221212011212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15223770115225 + 5987251096996 = 3901765^2 + 2446886^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21211021212221 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21211021212193 and 21211021212202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21211021212421) 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, 10605510606110 + 10605510606111.

It is an arithmetic number, because the mean of its divisors is an integer number (10605510606111).

Almost surely, 2^{21211021212221} is an apocalyptic number.

It is an amenable number.

21211021212221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211021212221 is an equidigital number, since it uses as much as digits as its factorization.

21211021212221 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 21211021212221 its reverse (12221212011212), we get a palindrome (33432233223433).

The spelling of 21211021212221 in words is "twenty-one trillion, two hundred eleven billion, twenty-one million, two hundred twelve thousand, two hundred twenty-one".