21212120111121 has 12 divisors (see below), whose sum is σ = 30639876841860. Its totient is φ = 14141345195520.

The previous prime is 21212120111087. The next prime is 21212120111129. The reversal of 21212120111121 is 12111102121212.

It is a happy number.

21212120111121 is a `hidden beast` number, since 212 + 121 + 201 + 11 + 121 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 1743825891600 + 19468294219521 = 1320540^2 + 4412289^2 .

It is not a de Polignac number, because 21212120111121 - 2¹⁸ = 21212119848977 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21212120111094 and 21212120111103.

It is not an unprimeable number, because it can be changed into a prime (21212120111129) 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 in 11 ways as a sum of consecutive naturals, for example, 3677536 + ... + 7479873.

It is an arithmetic number, because the mean of its divisors is an integer number (2553323070155).

Almost surely, 2^{21212120111121} is an apocalyptic number.

It is an amenable number.

21212120111121 is a deficient number, since it is larger than the sum of its proper divisors (9427756730739).

21212120111121 is a wasteful number, since it uses less digits than its factorization.

21212120111121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11368656 (or 11368653 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 18.

Adding to 21212120111121 its reverse (12111102121212), we get a palindrome (33323222232333).

The spelling of 21212120111121 in words is "twenty-one trillion, two hundred twelve billion, one hundred twenty million, one hundred eleven thousand, one hundred twenty-one".