21000203 has 4 divisors (see below), whose sum is σ = 24000240. Its totient is φ = 18000168.

The previous prime is 21000193. The next prime is 21000229. The reversal of 21000203 is 30200012.

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

It is a cyclic number.

It is not a de Polignac number, because 21000203 - 2⁶ = 21000139 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21000233) 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, 1500008 + ... + 1500021.

It is an arithmetic number, because the mean of its divisors is an integer number (6000060).

Almost surely, 2^21000203 is an apocalyptic number.

21000203 is a deficient number, since it is larger than the sum of its proper divisors (3000037).

21000203 is an equidigital number, since it uses as much as digits as its factorization.

21000203 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3000036.

The product of its (nonzero) digits is 12, while the sum is 8.

The square root of 21000203 is about 4582.5978440182. The cubic root of 21000203 is about 275.8933066219.

Adding to 21000203 its reverse (30200012), we get a palindrome (51200215).

The spelling of 21000203 in words is "twenty-one million, two hundred three", and thus it is an aban number.