21011111202221 has 4 divisors (see below), whose sum is σ = 24012698516832. Its totient is φ = 18009523887612.

The previous prime is 21011111202167. The next prime is 21011111202223. The reversal of 21011111202221 is 12220211111012.

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 21011111202221 - 2²⁶ = 21011044093357 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 21011111202221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011111202223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1500793657295 + ... + 1500793657308.

It is an arithmetic number, because the mean of its divisors is an integer number (6003174629208).

Almost surely, 2^{21011111202221} is an apocalyptic number.

It is an amenable number.

21011111202221 is a deficient number, since it is larger than the sum of its proper divisors (3001587314611).

21011111202221 is an equidigital number, since it uses as much as digits as its factorization.

21011111202221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3001587314610.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 21011111202221 its reverse (12220211111012), we get a palindrome (33231322313233).

The spelling of 21011111202221 in words is "twenty-one trillion, eleven billion, one hundred eleven million, two hundred two thousand, two hundred twenty-one".