21221211111 has 8 divisors (see below), whose sum is σ = 28295905920. Its totient is φ = 14146995192.

The previous prime is 21221211097. The next prime is 21221211113. The reversal of 21221211111 is 11111212212.

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 21221211111 - 2²¹ = 21219113959 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221211113) 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, 1096 + ... + 206018.

It is an arithmetic number, because the mean of its divisors is an integer number (3536988240).

Almost surely, 2^21221211111 is an apocalyptic number.

21221211111 is a deficient number, since it is larger than the sum of its proper divisors (7074694809).

21221211111 is a wasteful number, since it uses less digits than its factorization.

21221211111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 239445.

The product of its digits is 16, while the sum is 15.

Adding to 21221211111 its reverse (11111212212), we get a palindrome (32332423323).

It can be divided in two parts, 212212 and 11111, that multiplied together give a palindrome (2357887532).

The spelling of 21221211111 in words is "twenty-one billion, two hundred twenty-one million, two hundred eleven thousand, one hundred eleven".