21221121202221 has 4 divisors (see below), whose sum is σ = 28294828269632. Its totient is φ = 14147414134812.

The previous prime is 21221121202187. The next prime is 21221121202241. The reversal of 21221121202221 is 12220212112212.

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 not a de Polignac number, because 21221121202221 - 2⁷ = 21221121202093 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221121202241) 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, 3536853533701 + ... + 3536853533706.

It is an arithmetic number, because the mean of its divisors is an integer number (7073707067408).

Almost surely, 2^{21221121202221} is an apocalyptic number.

It is an amenable number.

21221121202221 is a deficient number, since it is larger than the sum of its proper divisors (7073707067411).

21221121202221 is an equidigital number, since it uses as much as digits as its factorization.

21221121202221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7073707067410.

The product of its (nonzero) digits is 256, while the sum is 21.

Adding to 21221121202221 its reverse (12220212112212), we get a palindrome (33441333314433).

Subtracting from 21221121202221 its reverse (12220212112212), we obtain a palindrome (9000909090009).

The spelling of 21221121202221 in words is "twenty-one trillion, two hundred twenty-one billion, one hundred twenty-one million, two hundred two thousand, two hundred twenty-one".