210221102091809 has 2 divisors, whose sum is σ = 210221102091810. Its totient is φ = 210221102091808.

The previous prime is 210221102091787. The next prime is 210221102091817. The reversal of 210221102091809 is 908190201122012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 170809739136400 + 39411362955409 = 13069420^2 + 6277847^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-210221102091809 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (210221102091859) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105110551045904 + 105110551045905.

It is an arithmetic number, because the mean of its divisors is an integer number (105110551045905).

Almost surely, 2^{210221102091809} is an apocalyptic number.

It is an amenable number.

210221102091809 is a deficient number, since it is larger than the sum of its proper divisors (1).

210221102091809 is an equidigital number, since it uses as much as digits as its factorization.

210221102091809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10368, while the sum is 38.

The spelling of 210221102091809 in words is "two hundred ten trillion, two hundred twenty-one billion, one hundred two million, ninety-one thousand, eight hundred nine".