21231112111 has 4 divisors (see below), whose sum is σ = 23161213224. Its totient is φ = 19301011000.

The previous prime is 21231112109. The next prime is 21231112127. The reversal of 21231112111 is 11121113212.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21231112111 - 2¹ = 21231112109 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21231112811) 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, 965050540 + ... + 965050561.

It is an arithmetic number, because the mean of its divisors is an integer number (5790303306).

Almost surely, 2^21231112111 is an apocalyptic number.

21231112111 is a deficient number, since it is larger than the sum of its proper divisors (1930101113).

21231112111 is a wasteful number, since it uses less digits than its factorization.

21231112111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1930101112.

The product of its digits is 24, while the sum is 16.

Adding to 21231112111 its reverse (11121113212), we get a palindrome (32352225323).

It can be divided in two parts, 212311 and 12111, that added together give a palindrome (224422).

The spelling of 21231112111 in words is "twenty-one billion, two hundred thirty-one million, one hundred twelve thousand, one hundred eleven".