Is 647 a prime number? What are the divisors of 647?

## Parity of 647

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

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## Is 647 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 647 is about 25.436.

Thus, the square root of 647 is not an integer, and therefore 647 is not a square number.

Anyway, 647 is a prime number, and a prime number cannot be a perfect square.

## What is the square number of 647?

The square of a number (here 647) is the result of the product of this number (647) by itself (i.e., 647 × 647); the square of 647 is sometimes called "raising 647 to the power 2", or "647 squared".

The square of 647 is 418 609 because 647 × 647 = 6472 = 418 609.

As a consequence, 647 is the square root of 418 609.

## Number of digits of 647

647 is a number with 3 digits.

## What are the multiples of 647?

The multiples of 647 are all integers evenly divisible by 647, that is all numbers such that the remainder of the division by 647 is zero. There are infinitely many multiples of 647. The smallest multiples of 647 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 647). 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 25.436). 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 647

• Preceding numbers: …645, 646
• Following numbers: 648, 649

### Nearest numbers from 647

• Preceding prime number: 643
• Following prime number: 653
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