21200221 has 4 divisors (see below), whose sum is σ = 24228832. Its totient is φ = 18171612.

The previous prime is 21200209. The next prime is 21200233. The reversal of 21200221 is 12200212.

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 an interprime number because it is at equal distance from previous prime (21200209) and next prime (21200233).

It is a cyclic number.

It is not a de Polignac number, because 21200221 - 2⁷ = 21200093 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21200198 and 21200207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21200281) 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, 1514295 + ... + 1514308.

It is an arithmetic number, because the mean of its divisors is an integer number (6057208).

Almost surely, 2^21200221 is an apocalyptic number.

It is an amenable number.

21200221 is a deficient number, since it is larger than the sum of its proper divisors (3028611).

21200221 is an equidigital number, since it uses as much as digits as its factorization.

21200221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3028610.

The product of its (nonzero) digits is 16, while the sum is 10.

The square root of 21200221 is about 4604.3697722924. The cubic root of 21200221 is about 276.7664624421.

Adding to 21200221 its reverse (12200212), we get a palindrome (33400433).

Subtracting from 21200221 its reverse (12200212), we obtain a palindrome (9000009).

The spelling of 21200221 in words is "twenty-one million, two hundred thousand, two hundred twenty-one".