40409 has 4 divisors (see below), whose sum is σ = 42804. Its totient is φ = 38016.

The previous prime is 40387. The next prime is 40423. The reversal of 40409 is 90404.

40409 is nontrivially palindromic in base 16.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 24025 + 16384 = 155^2 + 128^2 .

It is a cyclic number.

It is not a de Polignac number, because 40409 - 2⁸ = 40153 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17), and also a Moran number because the ratio is a prime number: 2377 = 40409 / (4 + 0 + 4 + 0 + 9).

It is a Duffinian number.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 40409.

It is not an unprimeable number, because it can be changed into a prime (40429) 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, 1172 + ... + 1205.

It is an arithmetic number, because the mean of its divisors is an integer number (10701).

2⁴⁰⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

40409 is a deficient number, since it is larger than the sum of its proper divisors (2395).

40409 is a wasteful number, since it uses less digits than its factorization.

40409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2394.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 40409 is about 201.0198995125. The cubic root of 40409 is about 34.3156872487.

The spelling of 40409 in words is "forty thousand, four hundred nine".