21221011111 has 8 divisors (see below), whose sum is σ = 22231891584. Its totient is φ = 20217483000.

The previous prime is 21221011079. The next prime is 21221011127. The reversal of 21221011111 is 11111012212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21221011111 - 2⁵ = 21221011079 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21221011091 and 21221011100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221011181) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1832181 + ... + 1843726.

It is an arithmetic number, because the mean of its divisors is an integer number (2778986448).

Almost surely, 2^21221011111 is an apocalyptic number.

21221011111 is a deficient number, since it is larger than the sum of its proper divisors (1010880473).

21221011111 is a wasteful number, since it uses less digits than its factorization.

21221011111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3676181.

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

Adding to 21221011111 its reverse (11111012212), we get a palindrome (32332023323).

It can be divided in two parts, 2122101 and 1111, that added together give a palindrome (2123212).

The spelling of 21221011111 in words is "twenty-one billion, two hundred twenty-one million, eleven thousand, one hundred eleven".