209161 has 4 divisors (see below), whose sum is σ = 214852. Its totient is φ = 203472.

The previous prime is 209159. The next prime is 209173. The reversal of 209161 is 161902.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 176400 + 32761 = 420^2 + 181^2 .

It is a cyclic number.

It is not a de Polignac number, because 209161 - 2¹ = 209159 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (209861) 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 3 ways as a sum of consecutive naturals, for example, 2790 + ... + 2863.

It is an arithmetic number, because the mean of its divisors is an integer number (53713).

2²⁰⁹¹⁶¹ is an apocalyptic number.

It is an amenable number.

209161 is a deficient number, since it is larger than the sum of its proper divisors (5691).

209161 is an equidigital number, since it uses as much as digits as its factorization.

209161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5690.

The product of its (nonzero) digits is 108, while the sum is 19.

The square root of 209161 is about 457.3412292807. The cubic root of 209161 is about 59.3599559300.

The spelling of 209161 in words is "two hundred nine thousand, one hundred sixty-one".