21131203 has 4 divisors (see below), whose sum is σ = 21224520. Its totient is φ = 21037888.

The previous prime is 21131191. The next prime is 21131251. The reversal of 21131203 is 30213112.

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 21131203 - 2¹⁷ = 21000131 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21131293) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46318 + ... + 46771.

It is an arithmetic number, because the mean of its divisors is an integer number (5306130).

Almost surely, 2^21131203 is an apocalyptic number.

21131203 is a deficient number, since it is larger than the sum of its proper divisors (93317).

21131203 is an equidigital number, since it uses as much as digits as its factorization.

21131203 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93316.

The product of its (nonzero) digits is 36, while the sum is 13.

The square root of 21131203 is about 4596.8688256247. The cubic root of 21131203 is about 276.4657952275.

Adding to 21131203 its reverse (30213112), we get a palindrome (51344315).

The spelling of 21131203 in words is "twenty-one million, one hundred thirty-one thousand, two hundred three".