21404323 has 4 divisors (see below), whose sum is σ = 21453520. Its totient is φ = 21355128.

The previous prime is 21404321. The next prime is 21404359. The reversal of 21404323 is 32340412.

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 21404323 - 2¹ = 21404321 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 21404323.

It is not an unprimeable number, because it can be changed into a prime (21404321) 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, 23940 + ... + 24817.

It is an arithmetic number, because the mean of its divisors is an integer number (5363380).

Almost surely, 2^21404323 is an apocalyptic number.

21404323 is a deficient number, since it is larger than the sum of its proper divisors (49197).

21404323 is an equidigital number, since it uses as much as digits as its factorization.

21404323 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49196.

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

The square root of 21404323 is about 4626.4806278639. The cubic root of 21404323 is about 277.6518034235.

Adding to 21404323 its reverse (32340412), we get a palindrome (53744735).

The spelling of 21404323 in words is "twenty-one million, four hundred four thousand, three hundred twenty-three".