128209 has 4 divisors (see below), whose sum is σ = 132660. Its totient is φ = 123760.

The previous prime is 128203. The next prime is 128213. The reversal of 128209 is 902821.

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 88209 + 40000 = 297^2 + 200^2 .

It is a cyclic number.

It is not a de Polignac number, because 128209 - 2³ = 128201 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an Ulam number.

It is a Duffinian number.

128209 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 128209.

It is not an unprimeable number, because it can be changed into a prime (128201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2182 + ... + 2239.

It is an arithmetic number, because the mean of its divisors is an integer number (33165).

2¹²⁸²⁰⁹ is an apocalyptic number.

It is an amenable number.

128209 is a deficient number, since it is larger than the sum of its proper divisors (4451).

128209 is an equidigital number, since it uses as much as digits as its factorization.

128209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4450.

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 128209 is about 358.0628436462. The cubic root of 128209 is about 50.4242566114.

The spelling of 128209 in words is "one hundred twenty-eight thousand, two hundred nine".