21202010209 has 2 divisors, whose sum is σ = 21202010210. Its totient is φ = 21202010208.

The previous prime is 21202010201. The next prime is 21202010231. The reversal of 21202010209 is 90201020212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21045885184 + 156125025 = 145072^2 + 12495^2 .

It is a cyclic number.

It is not a de Polignac number, because 21202010209 - 2³ = 21202010201 is a prime.

It is not a weakly prime, because it can be changed into another prime (21202010201) 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, 10601005104 + 10601005105.

It is an arithmetic number, because the mean of its divisors is an integer number (10601005105).

Almost surely, 2^21202010209 is an apocalyptic number.

It is an amenable number.

21202010209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21202010209 is an equidigital number, since it uses as much as digits as its factorization.

21202010209 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 19.

The spelling of 21202010209 in words is "twenty-one billion, two hundred two million, ten thousand, two hundred nine".