21232221 has 8 divisors (see below), whose sum is σ = 28335360. Its totient is φ = 14141952.

The previous prime is 21232207. The next prime is 21232223. The reversal of 21232221 is 12223212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21232221 - 2⁶ = 21232157 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21232221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21232223) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1716 + ... + 6738.

It is an arithmetic number, because the mean of its divisors is an integer number (3541920).

Almost surely, 2^21232221 is an apocalyptic number.

It is an amenable number.

21232221 is a deficient number, since it is larger than the sum of its proper divisors (7103139).

21232221 is a wasteful number, since it uses less digits than its factorization.

21232221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6435.

The product of its digits is 96, while the sum is 15.

The square root of 21232221 is about 4607.8434218189. The cubic root of 21232221 is about 276.9056445520.

Adding to 21232221 its reverse (12223212), we get a palindrome (33455433).

Subtracting from 21232221 its reverse (12223212), we obtain a palindrome (9009009).

The spelling of 21232221 in words is "twenty-one million, two hundred thirty-two thousand, two hundred twenty-one".