21220111021 has 4 divisors (see below), whose sum is σ = 21224271232. Its totient is φ = 21215950812.

The previous prime is 21220110971. The next prime is 21220111027. The reversal of 21220111021 is 12011102212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21220111021 is a prime.

It is a super-2 number, since 2×21220111021² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21220110992 and 21220111010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220111027) 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, 2072445 + ... + 2082658.

It is an arithmetic number, because the mean of its divisors is an integer number (5306067808).

Almost surely, 2^21220111021 is an apocalyptic number.

It is an amenable number.

21220111021 is a deficient number, since it is larger than the sum of its proper divisors (4160211).

21220111021 is an equidigital number, since it uses as much as digits as its factorization.

21220111021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4160210.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21220111021 its reverse (12011102212), we get a palindrome (33231213233).

The spelling of 21220111021 in words is "twenty-one billion, two hundred twenty million, one hundred eleven thousand, twenty-one".