2121200021221 has 4 divisors (see below), whose sum is σ = 2122642034944. Its totient is φ = 2119758007500.

The previous prime is 2121200021219. The next prime is 2121200021231. The reversal of 2121200021221 is 1221200021212.

It is a happy number.

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 2121200021221 - 2¹ = 2121200021219 is a prime.

It is a super-3 number, since 3×2121200021221³ (a number of 38 digits) contains 333 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2121200021195 and 2121200021204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121200021231) 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, 721004655 + ... + 721007596.

It is an arithmetic number, because the mean of its divisors is an integer number (530660508736).

Almost surely, 2^{2121200021221} is an apocalyptic number.

It is an amenable number.

2121200021221 is a deficient number, since it is larger than the sum of its proper divisors (1442013723).

2121200021221 is a wasteful number, since it uses less digits than its factorization.

2121200021221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1442013722.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 2121200021221 its reverse (1221200021212), we get a palindrome (3342400042433).

Subtracting from 2121200021221 its reverse (1221200021212), we obtain a palindrome (900000000009).

The spelling of 2121200021221 in words is "two trillion, one hundred twenty-one billion, two hundred million, twenty-one thousand, two hundred twenty-one".