Is 555 a prime number?

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

For 555, the answer is: No, 555 is not a prime number.

The list of all positive divisors (i.e., the list of all integers that divide 555) is as follows: 1, 3, 5, 15, 37, 111, 185, 555.

For 555 to be a prime number, it would have been required that 555 has only two divisors, i.e., itself and 1.

Find out more:

What is a prime number?

Actually, one can immediately see that 555 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 555 is 5, so it is divisible by 5 and is therefore not prime.

As a consequence:

555 is a multiple of 1
555 is a multiple of 3
555 is a multiple of 5
555 is a multiple of 15
555 is a multiple of 37
555 is a multiple of 111
555 is a multiple of 185

For 555 to be a prime number, it would have been required that 555 has only two divisors, i.e., itself and 1.

Is 555 a deficient number?

Yes, 555 is a deficient number, that is to say 555 is a natural number that is strictly larger than the sum of its proper divisors, i.e., the divisors of 555 without 555 itself (that is 1 + 3 + 5 + 15 + 37 + 111 + 185 = 357).

Parity of 555

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

Find out more:

What is an even number?

Is 555 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 555 is about 23.558.

Thus, the square root of 555 is not an integer, and therefore 555 is not a square number.

What is the square number of 555?

The square of a number (here 555) is the result of the product of this number (555) by itself (i.e., 555 × 555); the square of 555 is sometimes called "raising 555 to the power 2", or "555 squared".

The square of 555 is 308 025 because 555 × 555 = 555² = 308 025.

As a consequence, 555 is the square root of 308 025.

Number of digits of 555

555 is a number with 3 digits.

What are the multiples of 555?

The multiples of 555 are all integers evenly divisible by 555, that is all numbers such that the remainder of the division by 555 is zero. There are infinitely many multiples of 555. The smallest multiples of 555 are:

0: indeed, 0 is divisible by any natural number, and it is thus a multiple of 555 too, since 0 × 555 = 0
555: indeed, 555 is a multiple of itself, since 555 is evenly divisible by 555 (we have 555 / 555 = 1, so the remainder of this division is indeed zero)
1 110: indeed, 1 110 = 555 × 2
1 665: indeed, 1 665 = 555 × 3
2 220: indeed, 2 220 = 555 × 4
2 775: indeed, 2 775 = 555 × 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 555). 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 23.558). 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 555

Preceding numbers: …553, 554
Following numbers: 556, 557…

Nearest numbers from 555

Preceding prime number: 547
Following prime number: 557