Is 668 a prime number?

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

For 668, the answer is: No, 668 is not a prime number.

The list of all positive divisors (i.e., the list of all integers that divide 668) is as follows: 1, 2, 4, 167, 334, 668.

For 668 to be a prime number, it would have been required that 668 has only two divisors, i.e., itself and 1.

Find out more:

What is a prime number?

As a consequence:

668 is a multiple of 1
668 is a multiple of 2
668 is a multiple of 4
668 is a multiple of 167
668 is a multiple of 334

For 668 to be a prime number, it would have been required that 668 has only two divisors, i.e., itself and 1.

Is 668 a deficient number?

Yes, 668 is a deficient number, that is to say 668 is a natural number that is strictly larger than the sum of its proper divisors, i.e., the divisors of 668 without 668 itself (that is 1 + 2 + 4 + 167 + 334 = 508).

Parity of 668

668 is an even number, because it is evenly divisible by 2: 668 / 2 = 334.

Find out more:

What is an even number?

Is 668 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 668 is about 25.846.

Thus, the square root of 668 is not an integer, and therefore 668 is not a square number.

What is the square number of 668?

The square of a number (here 668) is the result of the product of this number (668) by itself (i.e., 668 × 668); the square of 668 is sometimes called "raising 668 to the power 2", or "668 squared".

The square of 668 is 446 224 because 668 × 668 = 668² = 446 224.

As a consequence, 668 is the square root of 446 224.

Number of digits of 668

668 is a number with 3 digits.

What are the multiples of 668?

The multiples of 668 are all integers evenly divisible by 668, that is all numbers such that the remainder of the division by 668 is zero. There are infinitely many multiples of 668. The smallest multiples of 668 are:

0: indeed, 0 is divisible by any natural number, and it is thus a multiple of 668 too, since 0 × 668 = 0
668: indeed, 668 is a multiple of itself, since 668 is evenly divisible by 668 (we have 668 / 668 = 1, so the remainder of this division is indeed zero)
1 336: indeed, 1 336 = 668 × 2
2 004: indeed, 2 004 = 668 × 3
2 672: indeed, 2 672 = 668 × 4
3 340: indeed, 3 340 = 668 × 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 668). 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 25.846). 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 668

Preceding numbers: …666, 667
Following numbers: 669, 670…

Nearest numbers from 668

Preceding prime number: 661
Following prime number: 673