21202220121221 has 4 divisors (see below), whose sum is σ = 21204294103872. Its totient is φ = 21200146138572.

The previous prime is 21202220121209. The next prime is 21202220121241. The reversal of 21202220121221 is 12212102220212.

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 21202220121221 - 2²⁶ = 21202153012357 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21202220121193 and 21202220121202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21202220121241) 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, 1036975991 + ... + 1036996436.

It is an arithmetic number, because the mean of its divisors is an integer number (5301073525968).

Almost surely, 2^{21202220121221} is an apocalyptic number.

It is an amenable number.

21202220121221 is a deficient number, since it is larger than the sum of its proper divisors (2073982651).

21202220121221 is a wasteful number, since it uses less digits than its factorization.

21202220121221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2073982650.

The product of its (nonzero) digits is 256, while the sum is 20.

Adding to 21202220121221 its reverse (12212102220212), we get a palindrome (33414322341433).

The spelling of 21202220121221 in words is "twenty-one trillion, two hundred two billion, two hundred twenty million, one hundred twenty-one thousand, two hundred twenty-one".