21111111021121 has 4 divisors (see below), whose sum is σ = 23030302932144. Its totient is φ = 19191919110100.

The previous prime is 21111111021103. The next prime is 21111111021257. The reversal of 21111111021121 is 12112011111112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21111111021121 - 2³⁵ = 21076751282753 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21111111021095 and 21111111021104.

It is not an unprimeable number, because it can be changed into a prime (21111111721121) 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 3 ways as a sum of consecutive naturals, for example, 959595955495 + ... + 959595955516.

It is an arithmetic number, because the mean of its divisors is an integer number (5757575733036).

Almost surely, 2^{21111111021121} is an apocalyptic number.

It is an amenable number.

21111111021121 is a deficient number, since it is larger than the sum of its proper divisors (1919191911023).

21111111021121 is a wasteful number, since it uses less digits than its factorization.

21111111021121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1919191911022.

The product of its (nonzero) digits is 8, while the sum is 16.

Adding to 21111111021121 its reverse (12112011111112), we get a palindrome (33223122132233).

The spelling of 21111111021121 in words is "twenty-one trillion, one hundred eleven billion, one hundred eleven million, twenty-one thousand, one hundred twenty-one".