21331221311 has 4 divisors (see below), whose sum is σ = 21542421624. Its totient is φ = 21120021000.

The previous prime is 21331221271. The next prime is 21331221319. The reversal of 21331221311 is 11312213312.

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-21331221311 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 (21331221319) 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, 105600005 + ... + 105600206.

It is an arithmetic number, because the mean of its divisors is an integer number (5385605406).

Almost surely, 2^21331221311 is an apocalyptic number.

21331221311 is a deficient number, since it is larger than the sum of its proper divisors (211200313).

21331221311 is a wasteful number, since it uses less digits than its factorization.

21331221311 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 211200312.

The product of its digits is 216, while the sum is 20.

Adding to 21331221311 its reverse (11312213312), we get a palindrome (32643434623).

The spelling of 21331221311 in words is "twenty-one billion, three hundred thirty-one million, two hundred twenty-one thousand, three hundred eleven".