21604384 has 24 divisors (see below), whose sum is σ = 43258320. Its totient is φ = 10618176.

The previous prime is 21604381. The next prime is 21604393. The reversal of 21604384 is 48340612.

It is not an unprimeable number, because it can be changed into a prime (21604381) 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, 3834 + ... + 7609.

It is an arithmetic number, because the mean of its divisors is an integer number (1802430).

Almost surely, 2^21604384 is an apocalyptic number.

It is an amenable number.

21604384 is an abundant number, since it is smaller than the sum of its proper divisors (21653936).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21604384 is a wasteful number, since it uses less digits than its factorization.

21604384 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11512 (or 11504 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 28.

The square root of 21604384 is about 4648.0516348251. The cubic root of 21604384 is about 278.5141701547.

Adding to 21604384 its reverse (48340612), we get a palindrome (69944996).

The spelling of 21604384 in words is "twenty-one million, six hundred four thousand, three hundred eighty-four".