21530204 has 12 divisors (see below), whose sum is σ = 37848384. Its totient is φ = 10716384.

The previous prime is 21530161. The next prime is 21530227. The reversal of 21530204 is 40203512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11177 + ... + 12960.

It is an arithmetic number, because the mean of its divisors is an integer number (3154032).

Almost surely, 2^21530204 is an apocalyptic number.

It is an amenable number.

21530204 is a deficient number, since it is larger than the sum of its proper divisors (16318180).

21530204 is a wasteful number, since it uses less digits than its factorization.

21530204 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24364 (or 24362 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 21530204 is about 4640.0650857504. The cubic root of 21530204 is about 278.1950393653.

Adding to 21530204 its reverse (40203512), we get a palindrome (61733716).

The spelling of 21530204 in words is "twenty-one million, five hundred thirty thousand, two hundred four".