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Primes, Prime Factors

This app lets you
• check numbers to see if they are prime numbers,
• find next prime,
• find primes within an interval (range), and
• determining prime factors.
The input numbers need be between 0 and 9,223,372,036,854,775,807, which is 2^63-1, or approximately 9.223·10^18. Just keep numbers less than 19 digits; a validation mechanism prevents illegal input.

A prime number (or a prime) is a natural number greater than 1 that has no positive divisors other than 1 and itself. Examples: 2, 3, 5, 7, 11, 13, 17. 2 is the only even prime.
When finding primes in an interval, duration is shown, so the app may be used for benchmarking as well.

Prime factor
A natural number greater than 1 that is not a prime number is called a composite number. Enter any number into the Factor field, to get its prime factors. If the number is a prime, then it has only one factor, itself.
•Entering 6, gives 2 3.
•Entering 12, gives 2 2 3.
•Entering 100, gives 2 2 5 5.
Since very big numbers may consist of many small primes, prime factorization of large numbers may be very quick. Try it out.
Duration is shown.

I have tried to translate this app into every language imaginable, but I have used an online translation service for most of them, and as you know, words may have different meanings.
Please do not hesitate to email me, if you have any corrections to the translations, or just any tips or criticism to this app. I will read every mail — if it is written in English :)

What’s New

Version 1.3.2

This app has been updated by Apple to display the Apple Watch app icon.


Ratings and Reviews

4.3 out of 5
6 Ratings

6 Ratings

App Privacy

The developer, Henning Poulsen, has not provided details about its privacy practices and handling of data to Apple. For more information, see the developer’s privacy policy.

No Details Provided

The developer will be required to provide privacy details when they submit their next app update.


  • Family Sharing

    Up to six family members will be able to use this app with Family Sharing enabled.

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