Is 257 a prime number? What are the divisors of 257?

## Parity of 257

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

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## Is 257 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 257 is about 16.031.

Thus, the square root of 257 is not an integer, and therefore 257 is not a square number.

Anyway, 257 is a prime number, and a prime number cannot be a perfect square.

## What is the square number of 257?

The square of a number (here 257) is the result of the product of this number (257) by itself (i.e., 257 × 257); the square of 257 is sometimes called "raising 257 to the power 2", or "257 squared".

The square of 257 is 66 049 because 257 × 257 = 2572 = 66 049.

As a consequence, 257 is the square root of 66 049.

## Number of digits of 257

257 is a number with 3 digits.

## What are the multiples of 257?

The multiples of 257 are all integers evenly divisible by 257, that is all numbers such that the remainder of the division by 257 is zero. There are infinitely many multiples of 257. The smallest multiples of 257 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 257). 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 16.031). 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 257

• Preceding numbers: …255, 256
• Following numbers: 258, 259

### Nearest numbers from 257

• Preceding prime number: 251
• Following prime number: 263
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