Divisors of 991
Parity of 991
991is an odd number,as it is not divisible by 2
The factors for 991
The factors for 991 are all the numbers between -991 and 991 , which divide 991 without leaving any remainder. Since 991 divided by -991 is an integer, -991 is a factor of 991 .
Since 991 divided by -991 is a whole number, -991 is a factor of 991
Since 991 divided by -1 is a whole number, -1 is a factor of 991
Since 991 divided by 1 is a whole number, 1 is a factor of 991
What are the multiples of 991?
Multiples of 991 are all integers divisible by 991 , i.e. the remainder of the full division by 991 is zero. There are infinite multiples of 991. The smallest multiples of 991 are:
0 : in fact, 0 is divisible by any integer, so it is also a multiple of 991 since 0 × 991 = 0
991 : in fact, 991 is a multiple of itself, since 991 is divisible by 991 (it was 991 / 991 = 1, so the rest of this division is zero)
etc.
Is 991 a prime number?
It is possible to determine using mathematical techniques whether an integer is prime or not.
for 991, the answer is: yes, 991 is a prime number because it only has two different divisors: 1 and itself (991).
How do you determine if a number is prime?
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 991). 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 31.48 ). 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.
Numbers about 991
Previous Numbers: ... 989, 990
Prime numbers closer to 991
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Next prime number: 997