210009 has 4 divisors (see below), whose sum is σ = 280016. Its totient is φ = 140004.

The previous prime is 209987. The next prime is 210011. The reversal of 210009 is 900012.

It is a happy number.

210009 is digitally balanced in base 2, 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 210009 - 2⁵ = 209977 is a prime.

It is a D-number.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 209976 and 210003.

It is not an unprimeable number, because it can be changed into a prime (210019) 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, 34999 + ... + 35004.

It is an arithmetic number, because the mean of its divisors is an integer number (70004).

2²¹⁰⁰⁰⁹ is an apocalyptic number.

It is an amenable number.

210009 is a deficient number, since it is larger than the sum of its proper divisors (70007).

210009 is an equidigital number, since it uses as much as digits as its factorization.

210009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70006.

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

The square root of 210009 is about 458.2673891954. The cubic root of 210009 is about 59.4400686472.

It can be divided in two parts, 2 and 10009, that added together give a triangular number (10011 = T₁₄₁).

The spelling of 210009 in words is "two hundred ten thousand, nine".