21303223 has 4 divisors (see below), whose sum is σ = 21514248. Its totient is φ = 21092200.

The previous prime is 21303209. The next prime is 21303229. The reversal of 21303223 is 32230312.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21303223 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21303197 and 21303206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21303229) 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, 105361 + ... + 105562.

It is an arithmetic number, because the mean of its divisors is an integer number (5378562).

Almost surely, 2^21303223 is an apocalyptic number.

21303223 is a deficient number, since it is larger than the sum of its proper divisors (211025).

21303223 is a wasteful number, since it uses less digits than its factorization.

21303223 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 211024.

The product of its (nonzero) digits is 216, while the sum is 16.

The square root of 21303223 is about 4615.5414633605. The cubic root of 21303223 is about 277.2139649337.

Adding to 21303223 its reverse (32230312), we get a palindrome (53533535).

The spelling of 21303223 in words is "twenty-one million, three hundred three thousand, two hundred twenty-three".