20109 has 4 divisors (see below), whose sum is σ = 26816. Its totient is φ = 13404.

The previous prime is 20107. The next prime is 20113. The reversal of 20109 is 90102.

It is a happy number.

20109 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

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 20109 - 2¹ = 20107 is a prime.

It is a D-number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20094 and 20103.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20101) 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, 3349 + ... + 3354.

It is an arithmetic number, because the mean of its divisors is an integer number (6704).

2²⁰¹⁰⁹ is an apocalyptic number.

It is an amenable number.

20109 is a deficient number, since it is larger than the sum of its proper divisors (6707).

20109 is an equidigital number, since it uses as much as digits as its factorization.

20109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6706.

The product of its (nonzero) digits is 18, while the sum is 12.

The square root of 20109 is about 141.8062057880. The cubic root of 20109 is about 27.1933987729.

The spelling of 20109 in words is "twenty thousand, one hundred nine".