Is 420 a prime number? What are the divisors of 420?

## Parity of 420

420 is an even number, because it is evenly divisible by 2: 420 / 2 = 210.

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## Is 420 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 420 is about 20.494.

Thus, the square root of 420 is not an integer, and therefore 420 is not a square number.

## What is the square number of 420?

The square of a number (here 420) is the result of the product of this number (420) by itself (i.e., 420 × 420); the square of 420 is sometimes called "raising 420 to the power 2", or "420 squared".

The square of 420 is 176 400 because 420 × 420 = 4202 = 176 400.

As a consequence, 420 is the square root of 176 400.

## Number of digits of 420

420 is a number with 3 digits.

## What are the multiples of 420?

The multiples of 420 are all integers evenly divisible by 420, that is all numbers such that the remainder of the division by 420 is zero. There are infinitely many multiples of 420. The smallest multiples of 420 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 420). 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 20.494). 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 420

• Preceding numbers: …418, 419
• Following numbers: 421, 422

### Nearest numbers from 420

• Preceding prime number: 419
• Following prime number: 421
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