Is 255 a prime number? What are the divisors of 255?

## Parity of 255

255 is an odd number, because it is not evenly divisible by 2.

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## Is 255 a perfect square number?

A number is a perfect square (or a square number) if its square root is an integer; that is to say, it is the product of an integer with itself. Here, the square root of 255 is about 15.969.

Thus, the square root of 255 is not an integer, and therefore 255 is not a square number.

## What is the square number of 255?

The square of a number (here 255) is the result of the product of this number (255) by itself (i.e., 255 × 255); the square of 255 is sometimes called "raising 255 to the power 2", or "255 squared".

The square of 255 is 65 025 because 255 × 255 = 2552 = 65 025.

As a consequence, 255 is the square root of 65 025.

## Number of digits of 255

255 is a number with 3 digits.

## What are the multiples of 255?

The multiples of 255 are all integers evenly divisible by 255, that is all numbers such that the remainder of the division by 255 is zero. There are infinitely many multiples of 255. The smallest multiples of 255 are:

## How to determine whether an integer is a prime number?

To determine the primality of a number, several algorithms can be used. The most naive technique is to test all divisors strictly smaller to the number of which we want to determine the primality (here 255). First, we can eliminate all even numbers greater than 2 (and hence 4, 6, 8…). Then, we can stop this check when we reach the square root of the number of which we want to determine the primality (here the square root is about 15.969). Historically, the sieve of Eratosthenes (dating from the Greek mathematics) implements this technique in a relatively efficient manner.

More modern techniques include the sieve of Atkin, probabilistic algorithms, and the cyclotomic AKS test.

## Numbers near 255

• Preceding numbers: …253, 254
• Following numbers: 256, 257

### Nearest numbers from 255

• Preceding prime number: 251
• Following prime number: 257
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