Is 651 a prime number? What are the divisors of 651?

## Parity of 651

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

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## Is 651 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 651 is about 25.515.

Thus, the square root of 651 is not an integer, and therefore 651 is not a square number.

## What is the square number of 651?

The square of a number (here 651) is the result of the product of this number (651) by itself (i.e., 651 × 651); the square of 651 is sometimes called "raising 651 to the power 2", or "651 squared".

The square of 651 is 423 801 because 651 × 651 = 6512 = 423 801.

As a consequence, 651 is the square root of 423 801.

## Number of digits of 651

651 is a number with 3 digits.

## What are the multiples of 651?

The multiples of 651 are all integers evenly divisible by 651, that is all numbers such that the remainder of the division by 651 is zero. There are infinitely many multiples of 651. The smallest multiples of 651 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 651). 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 25.515). 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 651

• Preceding numbers: …649, 650
• Following numbers: 652, 653

### Nearest numbers from 651

• Preceding prime number: 647
• Following prime number: 653
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