128109 has 4 divisors (see below), whose sum is σ = 170816. Its totient is φ = 85404.

The previous prime is 128099. The next prime is 128111. The reversal of 128109 is 901821.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 128109 - 2⁹ = 127597 is a prime.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

128109 is a lucky number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 128109.

It is not an unprimeable number, because it can be changed into a prime (128119) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21349 + ... + 21354.

It is an arithmetic number, because the mean of its divisors is an integer number (42704).

2¹²⁸¹⁰⁹ is an apocalyptic number.

It is an amenable number.

128109 is a deficient number, since it is larger than the sum of its proper divisors (42707).

128109 is an equidigital number, since it uses as much as digits as its factorization.

128109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42706.

The product of its (nonzero) digits is 144, while the sum is 21.

The square root of 128109 is about 357.9231761147. The cubic root of 128109 is about 50.4111432907.

The spelling of 128109 in words is "one hundred twenty-eight thousand, one hundred nine".