21200121111221 has 24 divisors (see below), whose sum is σ = 24096536682624. Its totient is φ = 18538786859040.

The previous prime is 21200121111173. The next prime is 21200121111271. The reversal of 21200121111221 is 12211112100212.

It is not a de Polignac number, because 21200121111221 - 2¹⁸ = 21200120849077 is a prime.

It is a super-2 number, since 2×21200121111221² (a number of 27 digits) contains 22 as substring.

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 21200121111221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21200121111271) 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 23 ways as a sum of consecutive naturals, for example, 217363856 + ... + 217461366.

It is an arithmetic number, because the mean of its divisors is an integer number (1004022361776).

Almost surely, 2^{21200121111221} is an apocalyptic number.

It is an amenable number.

21200121111221 is a deficient number, since it is larger than the sum of its proper divisors (2896415571403).

21200121111221 is a wasteful number, since it uses less digits than its factorization.

21200121111221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143889 (or 143870 counting only the distinct ones).

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

Adding to 21200121111221 its reverse (12211112100212), we get a palindrome (33411233211433).

The spelling of 21200121111221 in words is "twenty-one trillion, two hundred billion, one hundred twenty-one million, one hundred eleven thousand, two hundred twenty-one".