21120111021221 has 4 divisors (see below), whose sum is σ = 21137267895744. Its totient is φ = 21102954146700.

The previous prime is 21120111021203. The next prime is 21120111021227. The reversal of 21120111021221 is 12212011102112.

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-21120111021221 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21120111021221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21120111021227) 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, 8578435415 + ... + 8578437876.

It is an arithmetic number, because the mean of its divisors is an integer number (5284316973936).

Almost surely, 2^{21120111021221} is an apocalyptic number.

It is an amenable number.

21120111021221 is a deficient number, since it is larger than the sum of its proper divisors (17156874523).

21120111021221 is a wasteful number, since it uses less digits than its factorization.

21120111021221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17156874522.

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

Adding to 21120111021221 its reverse (12212011102112), we get a palindrome (33332122123333).

The spelling of 21120111021221 in words is "twenty-one trillion, one hundred twenty billion, one hundred eleven million, twenty-one thousand, two hundred twenty-one".