21201212012209 has 2 divisors, whose sum is σ = 21201212012210. Its totient is φ = 21201212012208.

The previous prime is 21201212012177. The next prime is 21201212012243. The reversal of 21201212012209 is 90221021210212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20123550021184 + 1077661991025 = 4485928^2 + 1038105^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201212012209 - 2⁵ = 21201212012177 is a prime.

It is not a weakly prime, because it can be changed into another prime (21201212012509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600606006104 + 10600606006105.

It is an arithmetic number, because the mean of its divisors is an integer number (10600606006105).

Almost surely, 2^{21201212012209} is an apocalyptic number.

It is an amenable number.

21201212012209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201212012209 is an equidigital number, since it uses as much as digits as its factorization.

21201212012209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 576, while the sum is 25.

The spelling of 21201212012209 in words is "twenty-one trillion, two hundred one billion, two hundred twelve million, twelve thousand, two hundred nine".