21243233 has 4 divisors (see below), whose sum is σ = 23174448. Its totient is φ = 19312020.

The previous prime is 21243227. The next prime is 21243253. The reversal of 21243233 is 33234212.

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 a cyclic number.

It is not a de Polignac number, because 21243233 - 2¹⁸ = 20981089 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21243253) 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, 965591 + ... + 965612.

It is an arithmetic number, because the mean of its divisors is an integer number (5793612).

Almost surely, 2^21243233 is an apocalyptic number.

It is an amenable number.

21243233 is a deficient number, since it is larger than the sum of its proper divisors (1931215).

21243233 is a wasteful number, since it uses less digits than its factorization.

21243233 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1931214.

The product of its digits is 864, while the sum is 20.

The square root of 21243233 is about 4609.0381859993. The cubic root of 21243233 is about 276.9535082516.

Adding to 21243233 its reverse (33234212), we get a palindrome (54477445).

The spelling of 21243233 in words is "twenty-one million, two hundred forty-three thousand, two hundred thirty-three".