21322221 has 8 divisors (see below), whose sum is σ = 29410080. Its totient is φ = 13724592.

The previous prime is 21322207. The next prime is 21322229. The reversal of 21322221 is 12222312.

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 21322221 - 2⁹ = 21321709 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21322221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21322229) 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, 122455 + ... + 122628.

It is an arithmetic number, because the mean of its divisors is an integer number (3676260).

Almost surely, 2^21322221 is an apocalyptic number.

It is an amenable number.

21322221 is a deficient number, since it is larger than the sum of its proper divisors (8087859).

21322221 is a wasteful number, since it uses less digits than its factorization.

21322221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 245115.

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

The square root of 21322221 is about 4617.5990514552. The cubic root of 21322221 is about 277.2963459916.

Adding to 21322221 its reverse (12222312), we get a palindrome (33544533).

Subtracting from 21322221 its reverse (12222312), we obtain a palindrome (9099909).

The spelling of 21322221 in words is "twenty-one million, three hundred twenty-two thousand, two hundred twenty-one".