Is 775 a prime number?

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

For 775, the answer is: No, 775 is not a prime number.

The list of all positive divisors (i.e., the list of all integers that divide 775) is as follows: 1, 5, 25, 31, 155, 775.

For 775 to be a prime number, it would have been required that 775 has only two divisors, i.e., itself and 1.

Find out more:

What is a prime number?

Actually, one can immediately see that 775 cannot be prime, because 5 is one of its divisors: indeed, a number ending with 0 or 5 has necessarily 5 among its divisors. The last digit of 775 is 5, so it is divisible by 5 and is therefore not prime.

As a consequence:

775 is a multiple of 1
775 is a multiple of 5
775 is a multiple of 25
775 is a multiple of 31
775 is a multiple of 155

For 775 to be a prime number, it would have been required that 775 has only two divisors, i.e., itself and 1.

Is 775 a deficient number?

Yes, 775 is a deficient number, that is to say 775 is a natural number that is strictly larger than the sum of its proper divisors, i.e., the divisors of 775 without 775 itself (that is 1 + 5 + 25 + 31 + 155 = 217).

Parity of 775

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

Find out more:

What is an even number?

Is 775 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 775 is about 27.839.

Thus, the square root of 775 is not an integer, and therefore 775 is not a square number.

What is the square number of 775?

The square of a number (here 775) is the result of the product of this number (775) by itself (i.e., 775 × 775); the square of 775 is sometimes called "raising 775 to the power 2", or "775 squared".

The square of 775 is 600 625 because 775 × 775 = 775² = 600 625.

As a consequence, 775 is the square root of 600 625.

Number of digits of 775

775 is a number with 3 digits.

What are the multiples of 775?

The multiples of 775 are all integers evenly divisible by 775, that is all numbers such that the remainder of the division by 775 is zero. There are infinitely many multiples of 775. The smallest multiples of 775 are:

0: indeed, 0 is divisible by any natural number, and it is thus a multiple of 775 too, since 0 × 775 = 0
775: indeed, 775 is a multiple of itself, since 775 is evenly divisible by 775 (we have 775 / 775 = 1, so the remainder of this division is indeed zero)
1 550: indeed, 1 550 = 775 × 2
2 325: indeed, 2 325 = 775 × 3
3 100: indeed, 3 100 = 775 × 4
3 875: indeed, 3 875 = 775 × 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 775). 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 27.839). 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 775

Preceding numbers: …773, 774
Following numbers: 776, 777…

Nearest numbers from 775

Preceding prime number: 773
Following prime number: 787