Is 687 a prime number? What are the divisors of 687?

## Parity of 687

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

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## Is 687 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 687 is about 26.211.

Thus, the square root of 687 is not an integer, and therefore 687 is not a square number.

## What is the square number of 687?

The square of a number (here 687) is the result of the product of this number (687) by itself (i.e., 687 × 687); the square of 687 is sometimes called "raising 687 to the power 2", or "687 squared".

The square of 687 is 471 969 because 687 × 687 = 6872 = 471 969.

As a consequence, 687 is the square root of 471 969.

## Number of digits of 687

687 is a number with 3 digits.

## What are the multiples of 687?

The multiples of 687 are all integers evenly divisible by 687, that is all numbers such that the remainder of the division by 687 is zero. There are infinitely many multiples of 687. The smallest multiples of 687 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 687). 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 26.211). 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 687

• Preceding numbers: …685, 686
• Following numbers: 688, 689

### Nearest numbers from 687

• Preceding prime number: 683
• Following prime number: 691
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