21200111111221 has 4 divisors (see below), whose sum is σ = 24228698412832. Its totient is φ = 18171523809612.

The previous prime is 21200111111203. The next prime is 21200111111237. The reversal of 21200111111221 is 12211111100212.

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 not a de Polignac number, because 21200111111221 - 2⁷ = 21200111111093 is a prime.

It is a super-2 number, since 2×21200111111221² (a number of 27 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 = 21200111111195 and 21200111111204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21200111111261) 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, 1514293650795 + ... + 1514293650808.

It is an arithmetic number, because the mean of its divisors is an integer number (6057174603208).

Almost surely, 2^{21200111111221} is an apocalyptic number.

It is an amenable number.

21200111111221 is a deficient number, since it is larger than the sum of its proper divisors (3028587301611).

21200111111221 is an equidigital number, since it uses as much as digits as its factorization.

21200111111221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3028587301610.

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

Adding to 21200111111221 its reverse (12211111100212), we get a palindrome (33411222211433).

The spelling of 21200111111221 in words is "twenty-one trillion, two hundred billion, one hundred eleven million, one hundred eleven thousand, two hundred twenty-one".