Is 408 a prime number? What are the divisors of 408?

## Parity of 408

408 is an even number, because it is evenly divisible by 2: 408 / 2 = 204.

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## Is 408 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 408 is about 20.199.

Thus, the square root of 408 is not an integer, and therefore 408 is not a square number.

## What is the square number of 408?

The square of a number (here 408) is the result of the product of this number (408) by itself (i.e., 408 × 408); the square of 408 is sometimes called "raising 408 to the power 2", or "408 squared".

The square of 408 is 166 464 because 408 × 408 = 4082 = 166 464.

As a consequence, 408 is the square root of 166 464.

## Number of digits of 408

408 is a number with 3 digits.

## What are the multiples of 408?

The multiples of 408 are all integers evenly divisible by 408, that is all numbers such that the remainder of the division by 408 is zero. There are infinitely many multiples of 408. The smallest multiples of 408 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 408). 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 20.199). 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 408

• Preceding numbers: …406, 407
• Following numbers: 409, 410

### Nearest numbers from 408

• Preceding prime number: 401
• Following prime number: 409
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