161809 has 8 divisors (see below), whose sum is σ = 171072. Its totient is φ = 152880.

The previous prime is 161807. The next prime is 161831. The reversal of 161809 is 908161.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 161809 - 2¹ = 161807 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161807) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2244 + ... + 2314.

It is an arithmetic number, because the mean of its divisors is an integer number (21384).

2¹⁶¹⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

161809 is a deficient number, since it is larger than the sum of its proper divisors (9263).

161809 is an equidigital number, since it uses as much as digits as its factorization.

161809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 167.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 161809 is about 402.2548943145. The cubic root of 161809 is about 54.4921852836.

The spelling of 161809 in words is "one hundred sixty-one thousand, eight hundred nine".