21120211102121 has 4 divisors (see below), whose sum is σ = 21274373227092. Its totient is φ = 20966048977152.

The previous prime is 21120211102097. The next prime is 21120211102129. The reversal of 21120211102121 is 12120111202112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7743636342121 + 13376574760000 = 2782739^2 + 3657400^2 .

It is a cyclic number.

It is not a de Polignac number, because 21120211102121 - 2²⁶ = 21120143993257 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21120211102121.

It is not an unprimeable number, because it can be changed into a prime (21120211102129) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 77081062280 + ... + 77081062553.

It is an arithmetic number, because the mean of its divisors is an integer number (5318593306773).

Almost surely, 2^{21120211102121} is an apocalyptic number.

It is an amenable number.

21120211102121 is a deficient number, since it is larger than the sum of its proper divisors (154162124971).

21120211102121 is a wasteful number, since it uses less digits than its factorization.

21120211102121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154162124970.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 21120211102121 its reverse (12120111202112), we get a palindrome (33240322304233).

Subtracting from 21120211102121 its reverse (12120111202112), we obtain a palindrome (9000099900009).

The spelling of 21120211102121 in words is "twenty-one trillion, one hundred twenty billion, two hundred eleven million, one hundred two thousand, one hundred twenty-one".