21211222212181 has 2 divisors, whose sum is σ = 21211222212182. Its totient is φ = 21211222212180.

The previous prime is 21211222212137. The next prime is 21211222212269. The reversal of 21211222212181 is 18121222211212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11331773712900 + 9879448499281 = 3366270^2 + 3143159^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211222212181 - 2¹¹ = 21211222210133 is a prime.

It is a super-2 number, since 2×21211222212181² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21211222210181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605611106090 + 10605611106091.

It is an arithmetic number, because the mean of its divisors is an integer number (10605611106091).

Almost surely, 2^{21211222212181} is an apocalyptic number.

It is an amenable number.

21211222212181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211222212181 is an equidigital number, since it uses as much as digits as its factorization.

21211222212181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1024, while the sum is 28.

Adding to 21211222212181 its reverse (18121222211212), we get a palindrome (39332444423393).

The spelling of 21211222212181 in words is "twenty-one trillion, two hundred eleven billion, two hundred twenty-two million, two hundred twelve thousand, one hundred eighty-one".