# Difference between revisions of "Semiprime"

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==Examples== | ==Examples== | ||

− | *<math>9</math> is an example of a semiprime as it is the product of two threes. <math>3 | + | *<math>9</math> is an example of a semiprime as it is the product of two threes. <math>3*3=9</math>. |

*<math>10</math> is also an example as it is obtained by <math>5*2</math>. | *<math>10</math> is also an example as it is obtained by <math>5*2</math>. | ||

Other examples include: <math>25</math>, <math>15</math>, <math>39</math>, <math>221</math>, <math>437</math>, and <math>1537</math>. | Other examples include: <math>25</math>, <math>15</math>, <math>39</math>, <math>221</math>, <math>437</math>, and <math>1537</math>. |

## Latest revision as of 19:05, 28 May 2020

In mathematics, a **semiprime** is a number that is the product of two not necessarily distinct primes. These integers are important in many contexts, including cryptography.

## Examples

- is an example of a semiprime as it is the product of two threes. .
- is also an example as it is obtained by .

Other examples include: , , , , , and .

## Examples of non-semiprimes

- , as it is only a prime number.
- , not a semiprime because it can obtained by or .

## Basic Properties

Via the Sieve of Sundaram formulation of: being composite any time , as , we can show that if and only if are both not composite producing then is a semiprime.

Odd semiprimes, are able to be expressed as a difference of squares, like all other numbers that are products of numbers of same parity.

## See Also

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