1605409 has 4 divisors (see below), whose sum is σ = 1728916. Its totient is φ = 1481904.

The previous prime is 1605389. The next prime is 1605413. The reversal of 1605409 is 9045061.

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 305809 + 1299600 = 553^2 + 1140^2 .

It is a cyclic number.

It is not a de Polignac number, because 1605409 - 2¹¹ = 1603361 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1605419) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 61734 + ... + 61759.

It is an arithmetic number, because the mean of its divisors is an integer number (432229).

2^1605409 is an apocalyptic number.

It is an amenable number.

1605409 is a deficient number, since it is larger than the sum of its proper divisors (123507).

1605409 is a wasteful number, since it uses less digits than its factorization.

1605409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123506.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 1605409 is about 1267.0473550740. The cubic root of 1605409 is about 117.0923613841.

The spelling of 1605409 in words is "one million, six hundred five thousand, four hundred nine".