Is 778 a prime number?

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

For 778, the answer is: No, 778 is not a prime number.

The list of all positive divisors (i.e., the list of all integers that divide 778) is as follows: 1, 2, 389, 778.

For 778 to be a prime number, it would have been required that 778 has only two divisors, i.e., itself and 1.

Find out more:

What is a prime number?

As a consequence:

778 is a multiple of 1
778 is a multiple of 2
778 is a multiple of 389

For 778 to be a prime number, it would have been required that 778 has only two divisors, i.e., itself and 1.

However, 778 is a semiprime (also called biprime or 2-almost-prime), because it is the product of a two non-necessarily distinct prime numbers. Indeed, 778 = 2 x 389, where 2 and 389 are both prime numbers.

Is 778 a deficient number?

Yes, 778 is a deficient number, that is to say 778 is a natural number that is strictly larger than the sum of its proper divisors, i.e., the divisors of 778 without 778 itself (that is 1 + 2 + 389 = 392).

Parity of 778

778 is an even number, because it is evenly divisible by 2: 778 / 2 = 389.

Find out more:

What is an even number?

Is 778 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 778 is about 27.893.

Thus, the square root of 778 is not an integer, and therefore 778 is not a square number.

What is the square number of 778?

The square of a number (here 778) is the result of the product of this number (778) by itself (i.e., 778 × 778); the square of 778 is sometimes called "raising 778 to the power 2", or "778 squared".

The square of 778 is 605 284 because 778 × 778 = 778² = 605 284.

As a consequence, 778 is the square root of 605 284.

Number of digits of 778

778 is a number with 3 digits.

What are the multiples of 778?

The multiples of 778 are all integers evenly divisible by 778, that is all numbers such that the remainder of the division by 778 is zero. There are infinitely many multiples of 778. The smallest multiples of 778 are:

0: indeed, 0 is divisible by any natural number, and it is thus a multiple of 778 too, since 0 × 778 = 0
778: indeed, 778 is a multiple of itself, since 778 is evenly divisible by 778 (we have 778 / 778 = 1, so the remainder of this division is indeed zero)
1 556: indeed, 1 556 = 778 × 2
2 334: indeed, 2 334 = 778 × 3
3 112: indeed, 3 112 = 778 × 4
3 890: indeed, 3 890 = 778 × 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 778). 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 27.893). 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 778

Preceding numbers: …776, 777
Following numbers: 779, 780…

Nearest numbers from 778

Preceding prime number: 773
Following prime number: 787