21331223 has 4 divisors (see below), whose sum is σ = 21410208. Its totient is φ = 21252240.

The previous prime is 21331217. The next prime is 21331267. The reversal of 21331223 is 32213312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21331223 - 2¹⁶ = 21265687 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 (21331283) 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, 39086 + ... + 39627.

It is an arithmetic number, because the mean of its divisors is an integer number (5352552).

Almost surely, 2^21331223 is an apocalyptic number.

21331223 is a deficient number, since it is larger than the sum of its proper divisors (78985).

21331223 is an equidigital number, since it uses as much as digits as its factorization.

21331223 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78984.

The product of its digits is 216, while the sum is 17.

The square root of 21331223 is about 4618.5736975824. The cubic root of 21331223 is about 277.3353642924.

Adding to 21331223 its reverse (32213312), we get a palindrome (53544535).

The spelling of 21331223 in words is "twenty-one million, three hundred thirty-one thousand, two hundred twenty-three".