Is 291 a prime number?

It is possible to find out using mathematical methods whether a given integer is a prime number or not.

For 291, the answer is: No, 291 is not a prime number.

The list of all positive divisors (i.e., the list of all integers that divide 291) is as follows: 1, 3, 97, 291.

For 291 to be a prime number, it would have been required that 291 has only two divisors, i.e., itself and 1.

Find out more:

What is a prime number?

As a consequence:

291 is a multiple of 1
291 is a multiple of 3
291 is a multiple of 97

For 291 to be a prime number, it would have been required that 291 has only two divisors, i.e., itself and 1.

However, 291 is a semiprime (also called biprime or 2-almost-prime), because it is the product of a two non-necessarily distinct prime numbers. Indeed, 291 = 3 x 97, where 3 and 97 are both prime numbers.

Is 291 a deficient number?

Yes, 291 is a deficient number, that is to say 291 is a natural number that is strictly larger than the sum of its proper divisors, i.e., the divisors of 291 without 291 itself (that is 1 + 3 + 97 = 101).

Parity of 291

291 is an odd number, because it is not evenly divisible by 2.

Find out more:

What is an even number?

Is 291 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 291 is about 17.059.

Thus, the square root of 291 is not an integer, and therefore 291 is not a square number.

What is the square number of 291?

The square of a number (here 291) is the result of the product of this number (291) by itself (i.e., 291 × 291); the square of 291 is sometimes called "raising 291 to the power 2", or "291 squared".

The square of 291 is 84 681 because 291 × 291 = 291² = 84 681.

As a consequence, 291 is the square root of 84 681.

Number of digits of 291

291 is a number with 3 digits.

What are the multiples of 291?

The multiples of 291 are all integers evenly divisible by 291, that is all numbers such that the remainder of the division by 291 is zero. There are infinitely many multiples of 291. The smallest multiples of 291 are:

0: indeed, 0 is divisible by any natural number, and it is thus a multiple of 291 too, since 0 × 291 = 0
291: indeed, 291 is a multiple of itself, since 291 is evenly divisible by 291 (we have 291 / 291 = 1, so the remainder of this division is indeed zero)
582: indeed, 582 = 291 × 2
873: indeed, 873 = 291 × 3
1 164: indeed, 1 164 = 291 × 4
1 455: indeed, 1 455 = 291 × 5
etc.

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 291). 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 17.059). 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 291

Preceding numbers: …289, 290
Following numbers: 292, 293…

Nearest numbers from 291

Preceding prime number: 283
Following prime number: 293