21052304 has 80 divisors (see below), whose sum is σ = 52913280. Its totient is φ = 7879680.

The previous prime is 21052301. The next prime is 21052331. The reversal of 21052304 is 40325012.

It is not an unprimeable number, because it can be changed into a prime (21052301) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27284 + ... + 28044.

It is an arithmetic number, because the mean of its divisors is an integer number (661416).

Almost surely, 2^21052304 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21052304, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26456640).

21052304 is an abundant number, since it is smaller than the sum of its proper divisors (31860976).

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

21052304 is a wasteful number, since it uses less digits than its factorization.

21052304 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 808 (or 802 counting only the distinct ones).

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

The square root of 21052304 is about 4588.2789801842. The cubic root of 21052304 is about 276.1212797528.

Adding to 21052304 its reverse (40325012), we get a palindrome (61377316).

The spelling of 21052304 in words is "twenty-one million, fifty-two thousand, three hundred four".