240809 has 4 divisors (see below), whose sum is σ = 242004. Its totient is φ = 239616.

The previous prime is 240797. The next prime is 240811. The reversal of 240809 is 908042.

240809 is nontrivially palindromic in base 6.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 908042 = 2 ⋅454021.

It can be written as a sum of positive squares in 2 ways, for example, as 133225 + 107584 = 365^2 + 328^2 .

It is a cyclic number.

It is not a de Polignac number, because 240809 - 2¹² = 236713 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (240829) 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, 212 + ... + 725.

It is an arithmetic number, because the mean of its divisors is an integer number (60501).

2²⁴⁰⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

240809 is a deficient number, since it is larger than the sum of its proper divisors (1195).

240809 is an equidigital number, since it uses as much as digits as its factorization.

240809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1194.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 240809 is about 490.7229360851. The cubic root of 240809 is about 62.2143982273.

It can be divided in two parts, 2 and 40809, that multiplied together give a palindrome (81618).

The spelling of 240809 in words is "two hundred forty thousand, eight hundred nine".