21111223111 has 16 divisors (see below), whose sum is σ = 23799397248. Its totient is φ = 18560052000.

The previous prime is 21111223099. The next prime is 21111223129. The reversal of 21111223111 is 11132211112.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21111223111 - 2²¹ = 21109125959 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111223811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 173181 + ... + 268726.

It is an arithmetic number, because the mean of its divisors is an integer number (1487462328).

Almost surely, 2^21111223111 is an apocalyptic number.

21111223111 is a deficient number, since it is larger than the sum of its proper divisors (2688174137).

21111223111 is a wasteful number, since it uses less digits than its factorization.

21111223111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 442062.

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

Adding to 21111223111 its reverse (11132211112), we get a palindrome (32243434223).

The spelling of 21111223111 in words is "twenty-one billion, one hundred eleven million, two hundred twenty-three thousand, one hundred eleven".