21321323 has 4 divisors (see below), whose sum is σ = 21335808. Its totient is φ = 21306840.

The previous prime is 21321301. The next prime is 21321331. The reversal of 21321323 is 32312312.

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 21321323 - 2⁸ = 21321067 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (21321523) 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, 4748 + ... + 8073.

It is an arithmetic number, because the mean of its divisors is an integer number (5333952).

Almost surely, 2^21321323 is an apocalyptic number.

21321323 is a deficient number, since it is larger than the sum of its proper divisors (14485).

21321323 is a wasteful number, since it uses less digits than its factorization.

21321323 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14484.

The product of its digits is 216, while the sum is 17.

The square root of 21321323 is about 4617.5018137517. The cubic root of 21321323 is about 277.2924530948.

Adding to 21321323 its reverse (32312312), we get a palindrome (53633635).

The spelling of 21321323 in words is "twenty-one million, three hundred twenty-one thousand, three hundred twenty-three".