1809409 has 4 divisors (see below), whose sum is σ = 2067904. Its totient is φ = 1550916.

The previous prime is 1809403. The next prime is 1809413. The reversal of 1809409 is 9049081.

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: 9049081 = 1231 ⋅7351.

It is a cyclic number.

It is not a de Polignac number, because 1809409 - 2¹¹ = 1807361 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1809403) 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, 129237 + ... + 129250.

It is an arithmetic number, because the mean of its divisors is an integer number (516976).

2^1809409 is an apocalyptic number.

It is an amenable number.

1809409 is a deficient number, since it is larger than the sum of its proper divisors (258495).

1809409 is an equidigital number, since it uses as much as digits as its factorization.

1809409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 258494.

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 1809409 is about 1345.1427433548. The cubic root of 1809409 is about 121.8556251471.

The spelling of 1809409 in words is "one million, eight hundred nine thousand, four hundred nine".