409809 has 4 divisors (see below), whose sum is σ = 546416. Its totient is φ = 273204.

The previous prime is 409781. The next prime is 409813. The reversal of 409809 is 908904.

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 409809 - 2⁵ = 409777 is a prime.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (409879) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 68299 + ... + 68304.

It is an arithmetic number, because the mean of its divisors is an integer number (136604).

2⁴⁰⁹⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

409809 is a deficient number, since it is larger than the sum of its proper divisors (136607).

409809 is a wasteful number, since it uses less digits than its factorization.

409809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136606.

The product of its (nonzero) digits is 2592, while the sum is 30.

The square root of 409809 is about 640.1632604266. The cubic root of 409809 is about 74.2780505971.

The spelling of 409809 in words is "four hundred nine thousand, eight hundred nine".