21221212211 has 4 divisors (see below), whose sum is σ = 21225272712. Its totient is φ = 21217151712.

The previous prime is 21221212171. The next prime is 21221212213. The reversal of 21221212211 is 11221212212.

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 21221212211 - 2⁶ = 21221212147 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21221212211.

It is not an unprimeable number, because it can be changed into a prime (21221212213) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2022401 + ... + 2032866.

It is an arithmetic number, because the mean of its divisors is an integer number (5306318178).

Almost surely, 2^21221212211 is an apocalyptic number.

21221212211 is a deficient number, since it is larger than the sum of its proper divisors (4060501).

21221212211 is an equidigital number, since it uses as much as digits as its factorization.

21221212211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4060500.

The product of its digits is 64, while the sum is 17.

Adding to 21221212211 its reverse (11221212212), we get a palindrome (32442424423).

Subtracting from 21221212211 its reverse (11221212212), we obtain a palindrome (9999999999).

The spelling of 21221212211 in words is "twenty-one billion, two hundred twenty-one million, two hundred twelve thousand, two hundred eleven".