211021020209 has 2 divisors, whose sum is σ = 211021020210. Its totient is φ = 211021020208.

The previous prime is 211021020181. The next prime is 211021020239. The reversal of 211021020209 is 902020120112.

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., 209354747809 + 1666272400 = 457553^2 + 40820^2 .

It is a cyclic number.

It is not a de Polignac number, because 211021020209 - 2²⁰ = 211019971633 is a prime.

It is not a weakly prime, because it can be changed into another prime (211021020239) 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, 105510510104 + 105510510105.

It is an arithmetic number, because the mean of its divisors is an integer number (105510510105).

Almost surely, 2^211021020209 is an apocalyptic number.

It is an amenable number.

211021020209 is a deficient number, since it is larger than the sum of its proper divisors (1).

211021020209 is an equidigital number, since it uses as much as digits as its factorization.

211021020209 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 20.

The spelling of 211021020209 in words is "two hundred eleven billion, twenty-one million, twenty thousand, two hundred nine".