21003204 has 12 divisors (see below), whose sum is σ = 49007504. Its totient is φ = 7001064.

The previous prime is 21003179. The next prime is 21003223. The reversal of 21003204 is 40230012.

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-2 number, since 2×21003204² = 882269156531232, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (12), and also a Moran number because the ratio is a prime number: 1750267 = 21003204 / (2 + 1 + 0 + 0 + 3 + 2 + 0 + 4).

It is a self number, because there is not a number n which added to its sum of digits gives 21003204.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 875122 + ... + 875145.

Almost surely, 2^21003204 is an apocalyptic number.

It is an amenable number.

21003204 is an abundant number, since it is smaller than the sum of its proper divisors (28004300).

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

21003204 is a wasteful number, since it uses less digits than its factorization.

21003204 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1750274 (or 1750272 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 12.

The square root of 21003204 is about 4582.9252666828. The cubic root of 21003204 is about 275.9064480247.

Adding to 21003204 its reverse (40230012), we get a palindrome (61233216).

The spelling of 21003204 in words is "twenty-one million, three thousand, two hundred four".