21021203 has 4 divisors (see below), whose sum is σ = 24024240. Its totient is φ = 18018168.

The previous prime is 21021181. The next prime is 21021229. The reversal of 21021203 is 30212012.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21021203 - 2⁸ = 21020947 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21021263) 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, 1501508 + ... + 1501521.

It is an arithmetic number, because the mean of its divisors is an integer number (6006060).

Almost surely, 2^21021203 is an apocalyptic number.

21021203 is a deficient number, since it is larger than the sum of its proper divisors (3003037).

21021203 is an equidigital number, since it uses as much as digits as its factorization.

21021203 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3003036.

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 21021203 is about 4584.8885482637. Note that the first 3 decimals coincide. The cubic root of 21021203 is about 275.9852395313.

Adding to 21021203 its reverse (30212012), we get a palindrome (51233215).

The spelling of 21021203 in words is "twenty-one million, twenty-one thousand, two hundred three".