397is an odd number,as it is not divisible by 2
The factors for 397 are all the numbers between -397 and 397 , which divide 397 without leaving any remainder. Since 397 divided by -397 is an integer, -397 is a factor of 397 .
Since 397 divided by -397 is a whole number, -397 is a factor of 397
Since 397 divided by -1 is a whole number, -1 is a factor of 397
Multiples of 397 are all integers divisible by 397 , i.e. the remainder of the full division by 397 is zero. There are infinite multiples of 397. The smallest multiples of 397 are:
It is possible to determine using mathematical techniques whether an integer is prime or not.
for 397, the answer is: yes, 397 is a prime number because it only has two different divisors: 1 and itself (397).
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 397). 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 19.925 ). 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.
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