21243423 has 8 divisors (see below), whose sum is σ = 28377648. Its totient is φ = 14135744.

The previous prime is 21243403. The next prime is 21243437. The reversal of 21243423 is 32434212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21243423 - 2⁶ = 21243359 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21243423.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21243403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4686 + ... + 8027.

It is an arithmetic number, because the mean of its divisors is an integer number (3547206).

Almost surely, 2^21243423 is an apocalyptic number.

21243423 is a deficient number, since it is larger than the sum of its proper divisors (7134225).

21243423 is a wasteful number, since it uses less digits than its factorization.

21243423 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13273.

The product of its digits is 1152, while the sum is 21.

The square root of 21243423 is about 4609.0587976289. The cubic root of 21243423 is about 276.9543339421.

Adding to 21243423 its reverse (32434212), we get a palindrome (53677635).

The spelling of 21243423 in words is "twenty-one million, two hundred forty-three thousand, four hundred twenty-three".