Primality vs isPrime?
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Primality
This app determines if a given integer is prime or provides its prime factors. It also calculates the ordinal position of prime numbers found, up to a certain limit.
- Primality testing
- Prime factorization
- Prime ordinality calculation
- Large integer support (up to 999,999,999,999)
- Clean and simple interface
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The Primality App has a clean and simple, yet powerful, function: Given any integer, the app determines either that the given integer is prime or else it provides all prime factors of that integer. Very clean, very simple, focussed. The app operates in the range of 0 - 999,999,999,999. A popular feature of the app is its ability to determine the prime ordinality of each prime found, such as observing that 97 if the 25th prime. (However, this particular feature is available only up to the 100,000th prime, which is 1,299,709.) Requires iOS 13 or higher.
isPrime?
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It's a fast prime number checker.
Screenshots
Verdict
The clearest difference is update cadence: isPrime? at daily against Primality's every 2 months. Primality's advantage is iOS requirement (13.2 vs 15.0). On price, ads, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
Primality ships an update every 2 months, isPrime? daily. The most recent releases landed on September 9, 2026 and September 20, 2026 respectively.
| Parameter | Primality | isPrime? |
|---|---|---|
| Price | Free | Free |
| Rating | 4.9 (24 ratings) — better | — |
| Positive reviews | 100.0% of reviews | — |
| Number of ratings | 24 — better | — |
| Update frequency | Every 2 months | Daily — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | — |
| Devices | iPhone, iPod | iPhone, iPod |
| Requires iOS | 13.2 — better | 15.0 |
| Further details — not scored | ||
| Size | 1 MB | 0 MB |
| Age rating | 4+ | 4+ |
| Developer | Bruce Schechter | Omer Faruk Mesebuken |
In-app purchases
Primality
No in-app purchases
isPrime?
No in-app purchases
