21111020121 has 16 divisors (see below), whose sum is σ = 29889216000. Its totient is φ = 13208164608.

The previous prime is 21111020111. The next prime is 21111020123. The reversal of 21111020121 is 12102011112.

It is not a de Polignac number, because 21111020121 - 2⁹ = 21111019609 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21111020097 and 21111020106.

It is not an unprimeable number, because it can be changed into a prime (21111020123) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 575241 + ... + 610838.

It is an arithmetic number, because the mean of its divisors is an integer number (1868076000).

Almost surely, 2^21111020121 is an apocalyptic number.

It is an amenable number.

21111020121 is a deficient number, since it is larger than the sum of its proper divisors (8778195879).

21111020121 is a wasteful number, since it uses less digits than its factorization.

21111020121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1186448.

The product of its (nonzero) digits is 8, while the sum is 12.

Adding to 21111020121 its reverse (12102011112), we get a palindrome (33213031233).

Subtracting from 21111020121 its reverse (12102011112), we obtain a palindrome (9009009009).

The spelling of 21111020121 in words is "twenty-one billion, one hundred eleven million, twenty thousand, one hundred twenty-one".