21323643 has 32 divisors (see below), whose sum is σ = 33177600. Its totient is φ = 12045600.

The previous prime is 21323641. The next prime is 21323647. The reversal of 21323643 is 34632312.

It is not a de Polignac number, because 21323643 - 2¹ = 21323641 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21323641) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 44278 + ... + 44756.

It is an arithmetic number, because the mean of its divisors is an integer number (1036800).

Almost surely, 2^21323643 is an apocalyptic number.

21323643 is a deficient number, since it is larger than the sum of its proper divisors (11853957).

21323643 is a wasteful number, since it uses less digits than its factorization.

21323643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 583.

The product of its digits is 2592, while the sum is 24.

The square root of 21323643 is about 4617.7530250112. The cubic root of 21323643 is about 277.3025102437.

Adding to 21323643 its reverse (34632312), we get a palindrome (55955955).

It can be divided in two parts, 2132 and 3643, that added together give a palindrome (5775).

The spelling of 21323643 in words is "twenty-one million, three hundred twenty-three thousand, six hundred forty-three".