21221213111 has 4 divisors (see below), whose sum is σ = 24252814992. Its totient is φ = 18189611232.

The previous prime is 21221213099. The next prime is 21221213119. The reversal of 21221213111 is 11131212212.

It is a happy number.

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 21221213111 - 2⁶ = 21221213047 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21221213111.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221213119) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1515800930 + ... + 1515800943.

It is an arithmetic number, because the mean of its divisors is an integer number (6063203748).

Almost surely, 2^21221213111 is an apocalyptic number.

21221213111 is a deficient number, since it is larger than the sum of its proper divisors (3031601881).

21221213111 is an equidigital number, since it uses as much as digits as its factorization.

21221213111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3031601880.

The product of its digits is 48, while the sum is 17.

Adding to 21221213111 its reverse (11131212212), we get a palindrome (32352425323).

The spelling of 21221213111 in words is "twenty-one billion, two hundred twenty-one million, two hundred thirteen thousand, one hundred eleven".