## Is 695 a prime number?

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

For 695, the answer is: No, 695 is not a prime number.

The list of all positive divisors (i.e., the list of all integers that divide 695) is as follows: 1, 5, 139, 695.

To be 695 a prime number, it would have been required that 695 has only two divisors, i.e., itself and 1.

As a consequence:

To be 695 a prime number, it would have been required that 695 has only two divisors, i.e., itself and 1.

However, 695 is a **semiprime** (also called biprime or 2-almost-prime), because it is the product of a two non-necessarily distinct prime numbers. Indeed, 695 = 5 x 139, where 5 and 139 are both prime numbers.

## Is 695 a deficient number?

Yes, 695 is a deficient number, that is to say 695 is a natural number that is strictly larger than the sum of its proper divisors, i.e., the divisors of 695 without 695 itself (that is 1 + 5 + 139 = 145).

## Parity of 695

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

## Is 695 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 695 is about 26.363.

Thus, the square root of 695 is not an integer, and therefore 695 is not a square number.

## What is the square number of 695?

The square of a number (here 695) is the result of the product of this number (695) by itself (i.e., 695 × 695); the square of 695 is sometimes called "raising 695 to the power 2", or "695 squared".

The square of 695 is 483 025 because 695 × 695 = 695^{2} = 483 025.

As a consequence, 695 is the square root of 483 025.

## Number of digits of 695

695 is a number with 3 digits.

## What are the multiples of 695?

The multiples of 695 are all integers evenly divisible by 695, that is all numbers such that the remainder of the division by 695 is zero. There are infinitely many multiples of 695. The smallest multiples of 695 are:

- 0: indeed, 0 is divisible by any natural number, and it is thus a multiple of 695 too, since 0 × 695 = 0
- 695: indeed, 695 is a multiple of itself, since 695 is evenly divisible by 695 (we have 695 / 695 = 1, so the remainder of this division is indeed zero)
- 1 390: indeed, 1 390 = 695 × 2
- 2 085: indeed, 2 085 = 695 × 3
- 2 780: indeed, 2 780 = 695 × 4
- 3 475: indeed, 3 475 = 695 × 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 695). 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 26.363). 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.