21201020111111 has 4 divisors (see below), whose sum is σ = 21201915108000. Its totient is φ = 21200125114224.

The previous prime is 21201020111039. The next prime is 21201020111123. The reversal of 21201020111111 is 11111102010212.

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 21201020111111 - 2³⁸ = 20926142204167 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201020111911) 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, 447462911 + ... + 447510288.

It is an arithmetic number, because the mean of its divisors is an integer number (5300478777000).

Almost surely, 2^{21201020111111} is an apocalyptic number.

21201020111111 is a deficient number, since it is larger than the sum of its proper divisors (894996889).

21201020111111 is an equidigital number, since it uses as much as digits as its factorization.

21201020111111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 894996888.

The product of its (nonzero) digits is 8, while the sum is 14.

Adding to 21201020111111 its reverse (11111102010212), we get a palindrome (32312122121323).

The spelling of 21201020111111 in words is "twenty-one trillion, two hundred one billion, twenty million, one hundred eleven thousand, one hundred eleven".