21121200111221 has 12 divisors (see below), whose sum is σ = 24716682432288. Its totient is φ = 17995479300792.

The previous prime is 21121200111161. The next prime is 21121200111239. The reversal of 21121200111221 is 12211100212112.

It is not a de Polignac number, because 21121200111221 - 2⁶ = 21121200111157 is a prime.

It is a super-2 number, since 2×21121200111221² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21121200111221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121200111421) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1290545411 + ... + 1290561776.

It is an arithmetic number, because the mean of its divisors is an integer number (2059723536024).

Almost surely, 2^{21121200111221} is an apocalyptic number.

It is an amenable number.

21121200111221 is a deficient number, since it is larger than the sum of its proper divisors (3595482321067).

21121200111221 is a wasteful number, since it uses less digits than its factorization.

21121200111221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2581107368 (or 2581107361 counting only the distinct ones).

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

Adding to 21121200111221 its reverse (12211100212112), we get a palindrome (33332300323333).

The spelling of 21121200111221 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred million, one hundred eleven thousand, two hundred twenty-one".