21112211111 has 4 divisors (see below), whose sum is σ = 21113910312. Its totient is φ = 21110511912.

The previous prime is 21112211059. The next prime is 21112211119. The reversal of 21112211111 is 11111221112.

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 21112211111 - 2⁶ = 21112211047 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 (21112211119) 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, 830825 + ... + 855858.

It is an arithmetic number, because the mean of its divisors is an integer number (5278477578).

Almost surely, 2^21112211111 is an apocalyptic number.

21112211111 is a deficient number, since it is larger than the sum of its proper divisors (1699201).

21112211111 is a wasteful number, since it uses less digits than its factorization.

21112211111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1699200.

The product of its digits is 8, while the sum is 14.

Adding to 21112211111 its reverse (11111221112), we get a palindrome (32223432223).

It can be divided in two parts, 2111221111 and 1, that added together give a palindrome (2111221112).

The spelling of 21112211111 in words is "twenty-one billion, one hundred twelve million, two hundred eleven thousand, one hundred eleven".