810209 has 2 divisors, whose sum is σ = 810210. Its totient is φ = 810208.

The previous prime is 810193. The next prime is 810223. The reversal of 810209 is 902018.

810209 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 483025 + 327184 = 695^2 + 572^2 .

It is a cyclic number.

It is not a de Polignac number, because 810209 - 2⁴ = 810193 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (810239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 405104 + 405105.

It is an arithmetic number, because the mean of its divisors is an integer number (405105).

2⁸¹⁰²⁰⁹ is an apocalyptic number.

It is an amenable number.

810209 is a deficient number, since it is larger than the sum of its proper divisors (1).

810209 is an equidigital number, since it uses as much as digits as its factorization.

810209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 810209 is about 900.1161036222. The cubic root of 810209 is about 93.2249919162.

Subtracting 810209 from its reverse (902018), we obtain a square (91809 = 303²).

The spelling of 810209 in words is "eight hundred ten thousand, two hundred nine".