21010212111209 has 2 divisors, whose sum is σ = 21010212111210. Its totient is φ = 21010212111208.

The previous prime is 21010212111179. The next prime is 21010212111223. The reversal of 21010212111209 is 90211121201012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20102193701209 + 908018410000 = 4483547^2 + 952900^2 .

It is a cyclic number.

It is not a de Polignac number, because 21010212111209 - 2¹² = 21010212107113 is a prime.

It is not a weakly prime, because it can be changed into another prime (21010212111709) 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, 10505106055604 + 10505106055605.

It is an arithmetic number, because the mean of its divisors is an integer number (10505106055605).

Almost surely, 2^{21010212111209} is an apocalyptic number.

It is an amenable number.

21010212111209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21010212111209 is an equidigital number, since it uses as much as digits as its factorization.

21010212111209 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 23.

The spelling of 21010212111209 in words is "twenty-one trillion, ten billion, two hundred twelve million, one hundred eleven thousand, two hundred nine".