21122111111111 has 4 divisors (see below), whose sum is σ = 22364588235312. Its totient is φ = 19879633986912.

The previous prime is 21122111111071. The next prime is 21122111111137. The reversal of 21122111111111 is 11111111122112.

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 21122111111111 - 2³⁰ = 21121037369287 is a prime.

It is a super-2 number, since 2×21122111111111² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (17), and also a Moran number because the ratio is a prime number: 1242477124183 = 21122111111111 / (2 + 1 + 1 + 2 + 2 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1).

It is a Duffinian number.

21122111111111 is a modest number, since divided by 11111111 gives 211221 as remainder.

It is a self number, because there is not a number n which added to its sum of digits gives 21122111111111.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21122111111141) 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, 621238562075 + ... + 621238562108.

It is an arithmetic number, because the mean of its divisors is an integer number (5591147058828).

Almost surely, 2^{21122111111111} is an apocalyptic number.

21122111111111 is a deficient number, since it is larger than the sum of its proper divisors (1242477124201).

21122111111111 is a wasteful number, since it uses less digits than its factorization.

21122111111111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1242477124200.

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

Adding to 21122111111111 its reverse (11111111122112), we get a palindrome (32233222233223).

The spelling of 21122111111111 in words is "twenty-one trillion, one hundred twenty-two billion, one hundred eleven million, one hundred eleven thousand, one hundred eleven".