170809 has 2 divisors, whose sum is σ = 170810. Its totient is φ = 170808.

The previous prime is 170801. The next prime is 170813. The reversal of 170809 is 908071.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 129600 + 41209 = 360^2 + 203^2 .

It is an emirp because it is prime and its reverse (908071) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 170809 - 2³ = 170801 is a prime.

170809 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (170801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 85404 + 85405.

It is an arithmetic number, because the mean of its divisors is an integer number (85405).

2¹⁷⁰⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

170809 is a deficient number, since it is larger than the sum of its proper divisors (1).

170809 is an equidigital number, since it uses as much as digits as its factorization.

170809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 504, while the sum is 25.

The square root of 170809 is about 413.2904547652. The cubic root of 170809 is about 55.4843177292.

It can be divided in two parts, 170 and 809, that added together give a palindrome (979).

The spelling of 170809 in words is "one hundred seventy thousand, eight hundred nine".