21323541 has 4 divisors (see below), whose sum is σ = 28431392. Its totient is φ = 14215692.

The previous prime is 21323531. The next prime is 21323591. The reversal of 21323541 is 14532312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21323541 - 2⁵ = 21323509 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21323521) 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, 3553921 + ... + 3553926.

It is an arithmetic number, because the mean of its divisors is an integer number (7107848).

Almost surely, 2^21323541 is an apocalyptic number.

It is an amenable number.

21323541 is a deficient number, since it is larger than the sum of its proper divisors (7107851).

21323541 is an equidigital number, since it uses as much as digits as its factorization.

21323541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7107850.

The product of its digits is 720, while the sum is 21.

The square root of 21323541 is about 4617.7419806654. The cubic root of 21323541 is about 277.3020680913.

Adding to 21323541 its reverse (14532312), we get a palindrome (35855853).

The spelling of 21323541 in words is "twenty-one million, three hundred twenty-three thousand, five hundred forty-one".