18005409 has 10 divisors (see below), whose sum is σ = 26897090. Its totient is φ = 12003552.

The previous prime is 18005401. The next prime is 18005411. The reversal of 18005409 is 90450081.

It can be written as a sum of positive squares in only one way, i.e., 14085009 + 3920400 = 3753^2 + 1980^2 .

It is not a de Polignac number, because 18005409 - 2³ = 18005401 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18005401) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 111064 + ... + 111225.

It is an arithmetic number, because the mean of its divisors is an integer number (2689709).

Almost surely, 2^18005409 is an apocalyptic number.

It is an amenable number.

18005409 is a deficient number, since it is larger than the sum of its proper divisors (8891681).

18005409 is an equidigital number, since it uses as much as digits as its factorization.

18005409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 222301 (or 222292 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The square root of 18005409 is about 4243.2780960008. The cubic root of 18005409 is about 262.1003878848.

The spelling of 18005409 in words is "eighteen million, five thousand, four hundred nine".