21121222111 has 16 divisors (see below), whose sum is σ = 24494198400. Its totient is φ = 18010404000.

The previous prime is 21121222099. The next prime is 21121222141. The reversal of 21121222111 is 11122212112.

It is not a de Polignac number, because 21121222111 - 2⁷ = 21121221983 is a prime.

It is a super-2 number, since 2×21121222111² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121222141) 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, 479181 + ... + 521398.

It is an arithmetic number, because the mean of its divisors is an integer number (1530887400).

Almost surely, 2^21121222111 is an apocalyptic number.

21121222111 is a deficient number, since it is larger than the sum of its proper divisors (3372976289).

21121222111 is a wasteful number, since it uses less digits than its factorization.

21121222111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1000710.

The product of its digits is 32, while the sum is 16.

Adding to 21121222111 its reverse (11122212112), we get a palindrome (32243434223).

Subtracting from 21121222111 its reverse (11122212112), we obtain a palindrome (9999009999).

The spelling of 21121222111 in words is "twenty-one billion, one hundred twenty-one million, two hundred twenty-two thousand, one hundred eleven".