21221110111 has 4 divisors (see below), whose sum is σ = 21568997224. Its totient is φ = 20873223000.

The previous prime is 21221110067. The next prime is 21221110187. The reversal of 21221110111 is 11101112212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21221110111 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21221110091 and 21221110100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221110411) 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, 173943465 + ... + 173943586.

It is an arithmetic number, because the mean of its divisors is an integer number (5392249306).

Almost surely, 2^21221110111 is an apocalyptic number.

21221110111 is a deficient number, since it is larger than the sum of its proper divisors (347887113).

21221110111 is an equidigital number, since it uses as much as digits as its factorization.

21221110111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 347887112.

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

Adding to 21221110111 its reverse (11101112212), we get a palindrome (32322222323).

The spelling of 21221110111 in words is "twenty-one billion, two hundred twenty-one million, one hundred ten thousand, one hundred eleven".