255809 has 4 divisors (see below), whose sum is σ = 264660. Its totient is φ = 246960.

The previous prime is 255803. The next prime is 255839. The reversal of 255809 is 908552.

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 148225 + 107584 = 385^2 + 328^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-255809 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29), and also a Moran number because the ratio is a prime number: 8821 = 255809 / (2 + 5 + 5 + 8 + 0 + 9).

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 255809.

It is not an unprimeable number, because it can be changed into a prime (255803) 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, 4382 + ... + 4439.

It is an arithmetic number, because the mean of its divisors is an integer number (66165).

2²⁵⁵⁸⁰⁹ is an apocalyptic number.

255809 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

255809 is a deficient number, since it is larger than the sum of its proper divisors (8851).

255809 is an equidigital number, since it uses as much as digits as its factorization.

255809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8850.

The product of its (nonzero) digits is 3600, while the sum is 29.

The square root of 255809 is about 505.7756419600. The cubic root of 255809 is about 63.4802468164.

The spelling of 255809 in words is "two hundred fifty-five thousand, eight hundred nine".