21001221203 has 2 divisors, whose sum is σ = 21001221204. Its totient is φ = 21001221202.

The previous prime is 21001221181. The next prime is 21001221229. The reversal of 21001221203 is 30212210012.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21001221203 - 2¹⁰ = 21001220179 is a prime.

It is not a weakly prime, because it can be changed into another prime (21001221503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500610601 + 10500610602.

It is an arithmetic number, because the mean of its divisors is an integer number (10500610602).

Almost surely, 2^21001221203 is an apocalyptic number.

21001221203 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001221203 is an equidigital number, since it uses as much as digits as its factorization.

21001221203 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48, while the sum is 14.

Adding to 21001221203 its reverse (30212210012), we get a palindrome (51213431215).

The spelling of 21001221203 in words is "twenty-one billion, one million, two hundred twenty-one thousand, two hundred three".