21331221211 has 4 divisors (see below), whose sum is σ = 21680913424. Its totient is φ = 20981529000.

The previous prime is 21331221161. The next prime is 21331221217. The reversal of 21331221211 is 11212213312.

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 21331221211 - 2⁹ = 21331220699 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21331221217) 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, 174846015 + ... + 174846136.

It is an arithmetic number, because the mean of its divisors is an integer number (5420228356).

Almost surely, 2^21331221211 is an apocalyptic number.

21331221211 is a deficient number, since it is larger than the sum of its proper divisors (349692213).

21331221211 is an equidigital number, since it uses as much as digits as its factorization.

21331221211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 349692212.

The product of its digits is 144, while the sum is 19.

Adding to 21331221211 its reverse (11212213312), we get a palindrome (32543434523).

The spelling of 21331221211 in words is "twenty-one billion, three hundred thirty-one million, two hundred twenty-one thousand, two hundred eleven".