21216203 has 2 divisors, whose sum is σ = 21216204. Its totient is φ = 21216202.

The previous prime is 21216199. The next prime is 21216241. The reversal of 21216203 is 30261212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21216203 - 2² = 21216199 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21216253) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10608101 + 10608102.

It is an arithmetic number, because the mean of its divisors is an integer number (10608102).

Almost surely, 2^21216203 is an apocalyptic number.

21216203 is a deficient number, since it is larger than the sum of its proper divisors (1).

21216203 is an equidigital number, since it uses as much as digits as its factorization.

21216203 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 21216203 is about 4606.1049705798. The cubic root of 21216203 is about 276.8359927009.

Adding to 21216203 its reverse (30261212), we get a palindrome (51477415).

The spelling of 21216203 in words is "twenty-one million, two hundred sixteen thousand, two hundred three".