21012203 has 4 divisors (see below), whose sum is σ = 21690048. Its totient is φ = 20334360.

The previous prime is 21012193. The next prime is 21012227. The reversal of 21012203 is 30221012.

It is a happy number.

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 21012203 - 2²⁴ = 4234987 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21012283) 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, 338876 + ... + 338937.

It is an arithmetic number, because the mean of its divisors is an integer number (5422512).

Almost surely, 2^21012203 is an apocalyptic number.

21012203 is a deficient number, since it is larger than the sum of its proper divisors (677845).

21012203 is an equidigital number, since it uses as much as digits as its factorization.

21012203 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 677844.

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

The square root of 21012203 is about 4583.9069580435. The cubic root of 21012203 is about 275.9458472136.

Adding to 21012203 its reverse (30221012), we get a palindrome (51233215).

The spelling of 21012203 in words is "twenty-one million, twelve thousand, two hundred three".