Is 787 a prime number?

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

Find out more:

• What is an even 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 787 is about 28.054.

Thus, the square root of 787 is not an integer, and therefore 787 is not a square number.

Anyway, 787 is a prime number, and a prime number cannot be a perfect square.

The square of a number (here 787) is the result of the product of this number (787) by itself (i.e., 787 × 787); the square of 787 is sometimes called "raising 787 to the power 2", or "787 squared".

The square of 787 is 619 369 because 787 × 787 = 787² = 619 369.

As a consequence, 787 is the square root of 619 369.

787 is a number with 3 digits.

The multiples of 787 are all integers evenly divisible by 787, that is all numbers such that the remainder of the division by 787 is zero. There are infinitely many multiples of 787. The smallest multiples of 787 are:

• 0: indeed, 0 is divisible by any natural number, and it is thus a multiple of 787 too, since 0 × 787 = 0
• 787: indeed, 787 is a multiple of itself, since 787 is evenly divisible by 787 (we have 787 / 787 = 1, so the remainder of this division is indeed zero)
• 1 574: indeed, 1 574 = 787 × 2
• 2 361: indeed, 2 361 = 787 × 3
• 3 148: indeed, 3 148 = 787 × 4
• 3 935: indeed, 3 935 = 787 × 5
• etc.

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 787). 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 28.054). 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.

• Preceding numbers: …785, 786
• Following numbers: 788, 789…

Nearest numbers from 787

• Preceding prime number: 773
• Following prime number: 797

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• 787 est-il un nombre premier ?