100209 has 4 divisors (see below), whose sum is σ = 133616. Its totient is φ = 66804.

The previous prime is 100207. The next prime is 100213. The reversal of 100209 is 902001.

It is a happy number.

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, and also an emirpimes, since its reverse is a distinct semiprime: 902001 = 3 ⋅300667.

It is not a de Polignac number, because 100209 - 2¹ = 100207 is a prime.

It is an Ulam number.

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 = 100194 and 100203.

It is not an unprimeable number, because it can be changed into a prime (100207) 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, 16699 + ... + 16704.

It is an arithmetic number, because the mean of its divisors is an integer number (33404).

2¹⁰⁰²⁰⁹ is an apocalyptic number.

It is an amenable number.

100209 is a deficient number, since it is larger than the sum of its proper divisors (33407).

100209 is an equidigital number, since it uses as much as digits as its factorization.

100209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33406.

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

The square root of 100209 is about 316.5580515482. The cubic root of 100209 is about 46.4482022368.

The spelling of 100209 in words is "one hundred thousand, two hundred nine".