21440323 has 4 divisors (see below), whose sum is σ = 21552768. Its totient is φ = 21327880.

The previous prime is 21440317. The next prime is 21440351. The reversal of 21440323 is 32304412.

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 21440323 - 2⁵ = 21440291 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21440323.

It is not an unprimeable number, because it can be changed into a prime (21441323) 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, 55936 + ... + 56317.

It is an arithmetic number, because the mean of its divisors is an integer number (5388192).

Almost surely, 2^21440323 is an apocalyptic number.

21440323 is a deficient number, since it is larger than the sum of its proper divisors (112445).

21440323 is a wasteful number, since it uses less digits than its factorization.

21440323 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112444.

The product of its (nonzero) digits is 576, while the sum is 19.

The square root of 21440323 is about 4630.3696396724. The cubic root of 21440323 is about 277.8073773910.

Adding to 21440323 its reverse (32304412), we get a palindrome (53744735).

The spelling of 21440323 in words is "twenty-one million, four hundred forty thousand, three hundred twenty-three".