21222312121 has 2 divisors, whose sum is σ = 21222312122. Its totient is φ = 21222312120.

The previous prime is 21222312079. The next prime is 21222312157. The reversal of 21222312121 is 12121322212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20980074025 + 242238096 = 144845^2 + 15564^2 .

It is a cyclic number.

It is not a de Polignac number, because 21222312121 - 2⁹ = 21222311609 is a prime.

It is a super-2 number, since 2×21222312121² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21222312821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10611156060 + 10611156061.

It is an arithmetic number, because the mean of its divisors is an integer number (10611156061).

Almost surely, 2^21222312121 is an apocalyptic number.

It is an amenable number.

21222312121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21222312121 is an equidigital number, since it uses as much as digits as its factorization.

21222312121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 192, while the sum is 19.

Adding to 21222312121 its reverse (12121322212), we get a palindrome (33343634333).

The spelling of 21222312121 in words is "twenty-one billion, two hundred twenty-two million, three hundred twelve thousand, one hundred twenty-one".