Is 355 a prime number?

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

For 355, the answer is: No, 355 is not a prime number.

The list of all positive divisors (i.e., the list of all integers that divide 355) is as follows: 1, 5, 71, 355.

For 355 to be a prime number, it would have been required that 355 has only two divisors, i.e., itself and 1.

Find out more:

What is a prime number?

Actually, one can immediately see that 355 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 355 is 5, so it is divisible by 5 and is therefore not prime.

As a consequence:

355 is a multiple of 1
355 is a multiple of 5
355 is a multiple of 71

For 355 to be a prime number, it would have been required that 355 has only two divisors, i.e., itself and 1.

However, 355 is a semiprime (also called biprime or 2-almost-prime), because it is the product of a two non-necessarily distinct prime numbers. Indeed, 355 = 5 x 71, where 5 and 71 are both prime numbers.

Is 355 a deficient number?

Yes, 355 is a deficient number, that is to say 355 is a natural number that is strictly larger than the sum of its proper divisors, i.e., the divisors of 355 without 355 itself (that is 1 + 5 + 71 = 77).

Parity of 355

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

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What is an even number?

Is 355 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 355 is about 18.841.

Thus, the square root of 355 is not an integer, and therefore 355 is not a square number.

What is the square number of 355?

The square of a number (here 355) is the result of the product of this number (355) by itself (i.e., 355 × 355); the square of 355 is sometimes called "raising 355 to the power 2", or "355 squared".

The square of 355 is 126 025 because 355 × 355 = 355² = 126 025.

As a consequence, 355 is the square root of 126 025.

Number of digits of 355

355 is a number with 3 digits.

What are the multiples of 355?

The multiples of 355 are all integers evenly divisible by 355, that is all numbers such that the remainder of the division by 355 is zero. There are infinitely many multiples of 355. The smallest multiples of 355 are:

0: indeed, 0 is divisible by any natural number, and it is thus a multiple of 355 too, since 0 × 355 = 0
355: indeed, 355 is a multiple of itself, since 355 is evenly divisible by 355 (we have 355 / 355 = 1, so the remainder of this division is indeed zero)
710: indeed, 710 = 355 × 2
1 065: indeed, 1 065 = 355 × 3
1 420: indeed, 1 420 = 355 × 4
1 775: indeed, 1 775 = 355 × 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 355). 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 18.841). 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 355

Preceding numbers: …353, 354
Following numbers: 356, 357…

Nearest numbers from 355

Preceding prime number: 353
Following prime number: 359