21201222211121 has 2 divisors, whose sum is σ = 21201222211122. Its totient is φ = 21201222211120.

The previous prime is 21201222211097. The next prime is 21201222211171. The reversal of 21201222211121 is 12111222210212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17513689324096 + 3687532887025 = 4184936^2 + 1920295^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21201222211121 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21201222211093 and 21201222211102.

It is not a weakly prime, because it can be changed into another prime (21201222211171) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600611105560 + 10600611105561.

It is an arithmetic number, because the mean of its divisors is an integer number (10600611105561).

Almost surely, 2^{21201222211121} is an apocalyptic number.

It is an amenable number.

21201222211121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201222211121 is an equidigital number, since it uses as much as digits as its factorization.

21201222211121 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 21201222211121 its reverse (12111222210212), we get a palindrome (33312444421333).

Subtracting from 21201222211121 its reverse (12111222210212), we obtain a palindrome (9090000000909).

The spelling of 21201222211121 in words is "twenty-one trillion, two hundred one billion, two hundred twenty-two million, two hundred eleven thousand, one hundred twenty-one".