421is an odd number,as it is not divisible by 2
The factors for 421 are all the numbers between -421 and 421 , which divide 421 without leaving any remainder. Since 421 divided by -421 is an integer, -421 is a factor of 421 .
Since 421 divided by -421 is a whole number, -421 is a factor of 421
Since 421 divided by -1 is a whole number, -1 is a factor of 421
Multiples of 421 are all integers divisible by 421 , i.e. the remainder of the full division by 421 is zero. There are infinite multiples of 421. The smallest multiples of 421 are:
It is possible to determine using mathematical techniques whether an integer is prime or not.
for 421, the answer is: yes, 421 is a prime number because it only has two different divisors: 1 and itself (421).
To know the primality of an integer, we can use several algorithms. The most naive is to try all divisors below the number you want to know if it is prime (in our case 421). We can already eliminate even numbers bigger than 2 (then 4 , 6 , 8 ...). Besides, we can stop at the square root of the number in question (here 20.518 ). Historically, the Eratosthenes screen (which dates back to Antiquity) uses this technique relatively effectively.
More modern techniques include the Atkin screen, probabilistic tests, or the cyclotomic test.
Previous prime number: 419
Next prime number: 431