Is 621 a prime number?

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

For 621, the answer is: No, 621 is not a prime number.

The list of all positive divisors (i.e., the list of all integers that divide 621) is as follows: 1, 3, 9, 23, 27, 69, 207, 621.

For 621 to be a prime number, it would have been required that 621 has only two divisors, i.e., itself and 1.

Find out more:

What is a prime number?

As a consequence:

621 is a multiple of 1
621 is a multiple of 3
621 is a multiple of 9
621 is a multiple of 23
621 is a multiple of 27
621 is a multiple of 69
621 is a multiple of 207

For 621 to be a prime number, it would have been required that 621 has only two divisors, i.e., itself and 1.

Is 621 a deficient number?

Yes, 621 is a deficient number, that is to say 621 is a natural number that is strictly larger than the sum of its proper divisors, i.e., the divisors of 621 without 621 itself (that is 1 + 3 + 9 + 23 + 27 + 69 + 207 = 339).

Parity of 621

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

Find out more:

What is an even number?

Is 621 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 621 is about 24.920.

Thus, the square root of 621 is not an integer, and therefore 621 is not a square number.

What is the square number of 621?

The square of a number (here 621) is the result of the product of this number (621) by itself (i.e., 621 × 621); the square of 621 is sometimes called "raising 621 to the power 2", or "621 squared".

The square of 621 is 385 641 because 621 × 621 = 621² = 385 641.

As a consequence, 621 is the square root of 385 641.

Number of digits of 621

621 is a number with 3 digits.

What are the multiples of 621?

The multiples of 621 are all integers evenly divisible by 621, that is all numbers such that the remainder of the division by 621 is zero. There are infinitely many multiples of 621. The smallest multiples of 621 are:

0: indeed, 0 is divisible by any natural number, and it is thus a multiple of 621 too, since 0 × 621 = 0
621: indeed, 621 is a multiple of itself, since 621 is evenly divisible by 621 (we have 621 / 621 = 1, so the remainder of this division is indeed zero)
1 242: indeed, 1 242 = 621 × 2
1 863: indeed, 1 863 = 621 × 3
2 484: indeed, 2 484 = 621 × 4
3 105: indeed, 3 105 = 621 × 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 621). 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 24.920). 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 621

Preceding numbers: …619, 620
Following numbers: 622, 623…

Nearest numbers from 621

Preceding prime number: 619
Following prime number: 631