Is 245 a prime number? What are the divisors of 245?

## Parity of 245

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

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## Is 245 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 245 is about 15.652.

Thus, the square root of 245 is not an integer, and therefore 245 is not a square number.

## What is the square number of 245?

The square of a number (here 245) is the result of the product of this number (245) by itself (i.e., 245 × 245); the square of 245 is sometimes called "raising 245 to the power 2", or "245 squared".

The square of 245 is 60 025 because 245 × 245 = 2452 = 60 025.

As a consequence, 245 is the square root of 60 025.

## Number of digits of 245

245 is a number with 3 digits.

## What are the multiples of 245?

The multiples of 245 are all integers evenly divisible by 245, that is all numbers such that the remainder of the division by 245 is zero. There are infinitely many multiples of 245. The smallest multiples of 245 are:

• 0: indeed, 0 is divisible by any natural number, and it is thus a multiple of 245 too, since 0 × 245 = 0
• 245: indeed, 245 is a multiple of itself, since 245 is evenly divisible by 245 (we have 245 / 245 = 1, so the remainder of this division is indeed zero)
• 490: indeed, 490 = 245 × 2
• 735: indeed, 735 = 245 × 3
• 980: indeed, 980 = 245 × 4
• 1 225: indeed, 1 225 = 245 × 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 245). 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 15.652). 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 245

• Preceding numbers: …243, 244
• Following numbers: 246, 247

### Nearest numbers from 245

• Preceding prime number: 241
• Following prime number: 251
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