21201112111 has 4 divisors (see below), whose sum is σ = 21202505712. Its totient is φ = 21199718512.

The previous prime is 21201112087. The next prime is 21201112139. The reversal of 21201112111 is 11121110212.

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 21201112111 - 2²¹ = 21199014959 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21201112091 and 21201112100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201112151) 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, 673726 + ... + 704491.

It is an arithmetic number, because the mean of its divisors is an integer number (5300626428).

Almost surely, 2^21201112111 is an apocalyptic number.

21201112111 is a deficient number, since it is larger than the sum of its proper divisors (1393601).

21201112111 is a wasteful number, since it uses less digits than its factorization.

21201112111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1393600.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21201112111 its reverse (11121110212), we get a palindrome (32322222323).

The spelling of 21201112111 in words is "twenty-one billion, two hundred one million, one hundred twelve thousand, one hundred eleven".