21122122122121 has 2 divisors, whose sum is σ = 21122122122122. Its totient is φ = 21122122122120.

The previous prime is 21122122122091. The next prime is 21122122122139. The reversal of 21122122122121 is 12122122122112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17658190687225 + 3463931434896 = 4202165^2 + 1861164^2 .

It is a cyclic number.

It is not a de Polignac number, because 21122122122121 - 2⁷ = 21122122121993 is a prime.

It is a super-2 number, since 2×21122122122121² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21122122122092 and 21122122122101.

It is not a weakly prime, because it can be changed into another prime (21122122122421) 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, 10561061061060 + 10561061061061.

It is an arithmetic number, because the mean of its divisors is an integer number (10561061061061).

Almost surely, 2^{21122122122121} is an apocalyptic number.

It is an amenable number.

21122122122121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21122122122121 is an equidigital number, since it uses as much as digits as its factorization.

21122122122121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 256, while the sum is 22.

Adding to 21122122122121 its reverse (12122122122112), we get a palindrome (33244244244233).

Subtracting from 21122122122121 its reverse (12122122122112), we obtain a palindrome (9000000000009).

The spelling of 21122122122121 in words is "twenty-one trillion, one hundred twenty-two billion, one hundred twenty-two million, one hundred twenty-two thousand, one hundred twenty-one".