21121111112111 has 16 divisors (see below), whose sum is σ = 21641778602400. Its totient is φ = 20607313586688.

The previous prime is 21121111112051. The next prime is 21121111112191. The reversal of 21121111112111 is 11121111112112.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21121111112111 - 2³⁰ = 21120037370287 is a prime.

It is a super-2 number, since 2×21121111112111² (a number of 27 digits) contains 22 as substring.

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 21121111112111.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121111112191) 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, 2781275 + ... + 7069491.

It is an arithmetic number, because the mean of its divisors is an integer number (1352611162650).

Almost surely, 2^{21121111112111} is an apocalyptic number.

21121111112111 is a deficient number, since it is larger than the sum of its proper divisors (520667490289).

21121111112111 is a wasteful number, since it uses less digits than its factorization.

21121111112111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4289018.

The product of its digits is 8, while the sum is 17.

Adding to 21121111112111 its reverse (11121111112112), we get a palindrome (32242222224223).

Subtracting from 21121111112111 its reverse (11121111112112), we obtain a palindrome (9999999999999).

The spelling of 21121111112111 in words is "twenty-one trillion, one hundred twenty-one billion, one hundred eleven million, one hundred twelve thousand, one hundred eleven".