845809 has 2 divisors, whose sum is σ = 845810. Its totient is φ = 845808.

The previous prime is 845777. The next prime is 845833. The reversal of 845809 is 908548.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 485809 + 360000 = 697^2 + 600^2 .

It is a cyclic number.

It is not a de Polignac number, because 845809 - 2⁵ = 845777 is a prime.

It is an Ulam number.

It is not a weakly prime, because it can be changed into another prime (845849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 422904 + 422905.

It is an arithmetic number, because the mean of its divisors is an integer number (422905).

2⁸⁴⁵⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

845809 is a deficient number, since it is larger than the sum of its proper divisors (1).

845809 is an equidigital number, since it uses as much as digits as its factorization.

845809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11520, while the sum is 34.

The square root of 845809 is about 919.6787482594. The cubic root of 845809 is about 94.5708808195.

The spelling of 845809 in words is "eight hundred forty-five thousand, eight hundred nine".