Is 805 a prime number? What are the divisors of 805?

## Parity of 805

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

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## Is 805 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 805 is about 28.373.

Thus, the square root of 805 is not an integer, and therefore 805 is not a square number.

## What is the square number of 805?

The square of a number (here 805) is the result of the product of this number (805) by itself (i.e., 805 × 805); the square of 805 is sometimes called "raising 805 to the power 2", or "805 squared".

The square of 805 is 648 025 because 805 × 805 = 8052 = 648 025.

As a consequence, 805 is the square root of 648 025.

## Number of digits of 805

805 is a number with 3 digits.

## What are the multiples of 805?

The multiples of 805 are all integers evenly divisible by 805, that is all numbers such that the remainder of the division by 805 is zero. There are infinitely many multiples of 805. The smallest multiples of 805 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 805). 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 28.373). 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 805

• Preceding numbers: …803, 804
• Following numbers: 806, 807

### Nearest numbers from 805

• Preceding prime number: 797
• Following prime number: 809
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