Is 669 a prime number?

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

For 669, the answer is: No, 669 is not a prime number.

The list of all positive divisors (i.e., the list of all integers that divide 669) is as follows: 1, 3, 223, 669.

For 669 to be a prime number, it would have been required that 669 has only two divisors, i.e., itself and 1.

Find out more:

What is a prime number?

As a consequence:

669 is a multiple of 1
669 is a multiple of 3
669 is a multiple of 223

For 669 to be a prime number, it would have been required that 669 has only two divisors, i.e., itself and 1.

However, 669 is a semiprime (also called biprime or 2-almost-prime), because it is the product of a two non-necessarily distinct prime numbers. Indeed, 669 = 3 x 223, where 3 and 223 are both prime numbers.

Is 669 a deficient number?

Yes, 669 is a deficient number, that is to say 669 is a natural number that is strictly larger than the sum of its proper divisors, i.e., the divisors of 669 without 669 itself (that is 1 + 3 + 223 = 227).

Parity of 669

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

Find out more:

What is an even number?

Is 669 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 669 is about 25.865.

Thus, the square root of 669 is not an integer, and therefore 669 is not a square number.

What is the square number of 669?

The square of a number (here 669) is the result of the product of this number (669) by itself (i.e., 669 × 669); the square of 669 is sometimes called "raising 669 to the power 2", or "669 squared".

The square of 669 is 447 561 because 669 × 669 = 669² = 447 561.

As a consequence, 669 is the square root of 447 561.

Number of digits of 669

669 is a number with 3 digits.

What are the multiples of 669?

The multiples of 669 are all integers evenly divisible by 669, that is all numbers such that the remainder of the division by 669 is zero. There are infinitely many multiples of 669. The smallest multiples of 669 are:

0: indeed, 0 is divisible by any natural number, and it is thus a multiple of 669 too, since 0 × 669 = 0
669: indeed, 669 is a multiple of itself, since 669 is evenly divisible by 669 (we have 669 / 669 = 1, so the remainder of this division is indeed zero)
1 338: indeed, 1 338 = 669 × 2
2 007: indeed, 2 007 = 669 × 3
2 676: indeed, 2 676 = 669 × 4
3 345: indeed, 3 345 = 669 × 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 669). 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 25.865). 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 669

Preceding numbers: …667, 668
Following numbers: 670, 671…

Nearest numbers from 669

Preceding prime number: 661
Following prime number: 673