21200100221221 has 4 divisors (see below), whose sum is σ = 21200116541344. Its totient is φ = 21200083901100.

The previous prime is 21200100221203. The next prime is 21200100221231. The reversal of 21200100221221 is 12212200100212.

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 21200100221221 - 2¹¹ = 21200100219173 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21200100221195 and 21200100221204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21200100221231) 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, 6025395 + ... + 8871616.

It is an arithmetic number, because the mean of its divisors is an integer number (5300029135336).

Almost surely, 2^{21200100221221} is an apocalyptic number.

It is an amenable number.

21200100221221 is a deficient number, since it is larger than the sum of its proper divisors (16320123).

21200100221221 is a wasteful number, since it uses less digits than its factorization.

21200100221221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16320122.

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

Adding to 21200100221221 its reverse (12212200100212), we get a palindrome (33412300321433).

The spelling of 21200100221221 in words is "twenty-one trillion, two hundred billion, one hundred million, two hundred twenty-one thousand, two hundred twenty-one".