21221111011 has 4 divisors (see below), whose sum is σ = 21237967800. Its totient is φ = 21204254224.

The previous prime is 21221110997. The next prime is 21221111029. The reversal of 21221111011 is 11011112212.

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 21221111011 - 2²¹ = 21219013859 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21221110982 and 21221111000.

It is not an unprimeable number, because it can be changed into a prime (21221111711) 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, 8426506 + ... + 8429023.

It is an arithmetic number, because the mean of its divisors is an integer number (5309491950).

Almost surely, 2^21221111011 is an apocalyptic number.

21221111011 is a deficient number, since it is larger than the sum of its proper divisors (16856789).

21221111011 is a wasteful number, since it uses less digits than its factorization.

21221111011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16856788.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21221111011 its reverse (11011112212), we get a palindrome (32232223223).

The spelling of 21221111011 in words is "twenty-one billion, two hundred twenty-one million, one hundred eleven thousand, eleven".