210105209 has 2 divisors, whose sum is σ = 210105210. Its totient is φ = 210105208.

The previous prime is 210105179. The next prime is 210105221. The reversal of 210105209 is 902501012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 122589184 + 87516025 = 11072^2 + 9355^2 .

It is a cyclic number.

It is not a de Polignac number, because 210105209 - 2¹⁶ = 210039673 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 (210105809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105052604 + 105052605.

It is an arithmetic number, because the mean of its divisors is an integer number (105052605).

Almost surely, 2^210105209 is an apocalyptic number.

It is an amenable number.

210105209 is a deficient number, since it is larger than the sum of its proper divisors (1).

210105209 is an equidigital number, since it uses as much as digits as its factorization.

210105209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 180, while the sum is 20.

The square root of 210105209 is about 14495.0063470148. The cubic root of 210105209 is about 594.4914412574.

The spelling of 210105209 in words is "two hundred ten million, one hundred five thousand, two hundred nine".