21443243 has 4 divisors (see below), whose sum is σ = 21640080. Its totient is φ = 21246408.

The previous prime is 21443221. The next prime is 21443263. The reversal of 21443243 is 34234412.

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 21443243 - 2⁸ = 21442987 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21443203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 98255 + ... + 98472.

It is an arithmetic number, because the mean of its divisors is an integer number (5410020).

Almost surely, 2^21443243 is an apocalyptic number.

21443243 is a deficient number, since it is larger than the sum of its proper divisors (196837).

21443243 is a wasteful number, since it uses less digits than its factorization.

21443243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196836.

The product of its digits is 2304, while the sum is 23.

The square root of 21443243 is about 4630.6849385377. The cubic root of 21443243 is about 277.8199885306.

Adding to 21443243 its reverse (34234412), we get a palindrome (55677655).

The spelling of 21443243 in words is "twenty-one million, four hundred forty-three thousand, two hundred forty-three".