21112111121111 has 4 divisors (see below), whose sum is σ = 21112251632472. Its totient is φ = 21111970609752.

The previous prime is 21112111121089. The next prime is 21112111121137. The reversal of 21112111121111 is 11112111121112.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21112111121111 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 21112111121111.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21112111171111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 70030061 + ... + 70330886.

It is an arithmetic number, because the mean of its divisors is an integer number (5278062908118).

Almost surely, 2^{21112111121111} is an apocalyptic number.

21112111121111 is a deficient number, since it is larger than the sum of its proper divisors (140511361).

21112111121111 is a wasteful number, since it uses less digits than its factorization.

21112111121111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140511360.

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

Adding to 21112111121111 its reverse (11112111121112), we get a palindrome (32224222242223).

Subtracting from 21112111121111 its reverse (11112111121112), we obtain a palindrome (9999999999999).

It can be divided in two parts, 21112 and 111121111, that multiplied together give a palindrome (2345988895432).

The spelling of 21112111121111 in words is "twenty-one trillion, one hundred twelve billion, one hundred eleven million, one hundred twenty-one thousand, one hundred eleven".