997is an odd number,as it is not divisible by 2
The factors for 997 are all the numbers between -997 and 997 , which divide 997 without leaving any remainder. Since 997 divided by -997 is an integer, -997 is a factor of 997 .
Since 997 divided by -997 is a whole number, -997 is a factor of 997
Since 997 divided by -1 is a whole number, -1 is a factor of 997
Since 997 divided by 1 is a whole number, 1 is a factor of 997
Multiples of 997 are all integers divisible by 997 , i.e. the remainder of the full division by 997 is zero. There are infinite multiples of 997. The smallest multiples of 997 are:
0 : in fact, 0 is divisible by any integer, so it is also a multiple of 997 since 0 × 997 = 0
997 : in fact, 997 is a multiple of itself, since 997 is divisible by 997 (it was 997 / 997 = 1, so the rest of this division is zero)
etc.
It is possible to determine using mathematical techniques whether an integer is prime or not.
for 997, the answer is: yes, 997 is a prime number because it only has two different divisors: 1 and itself (997).
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 997). 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 31.575 ). 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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