PrimeXTime vs Sosu der
Price, ratings, monetisation and update history for both games, side by side — with what reviewers say about each.
PrimeXTime
Engage your mind with a unique number-based puzzle game. Start with a random number and strategically divide by single-digit primes. Bump the number by multiplying by 10 and adding a digit to reach 1 and win.
- Number division by primes
- Strategic bumping mechanic
- Goal to reduce number to 1
- Brain exercise gameplay
- Simple, intuitive interface
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Kill some time and give your brain a little exercise at the same time with this simple game. You start with a random number and then start dividing by single-digit primes (2, 3, 5 or 7). When you can't do any more divisions you 'bump' the number -- multiplying by 10 and adding any single digit. You win the game by reducing the original number to 1.
Sosu der
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This app is a quiz application that determines whether a number is prime or composite and swipes the correct answer. A prime number is a natural number greater than 1 that is not divisible by any other number except 1 and the number itself. For example, 2, 3, 5, and 7 are single-digit prime numbers. Composite numbers (composite numbers) are natural numbers greater than 1 that are not prime and are represented by the product of smaller natural numbers (e.g., 4 = 2 x 2, 6 = 2 x 3). Through this app, you can test your judgment and reflexes while having fun learning these mathematical concepts. ... How many two-digit, three-digit, and four-digit prime numbers do you know? Translated with www.DeepL.com/Translator (free version)
Screenshots
Verdict
The clearest difference is ads: PrimeXTime at none against Sosu der's shown. Sosu der's advantage is iOS requirement (15.0 vs 17.6). On price, update cadence, 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.
Both ship on a similar rhythm, roughly every 4 months. The most recent releases landed on June 1, 2026 and September 13, 2026 respectively.
| Parameter | PrimeXTime | Sosu der |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (2 ratings) — better | — |
| Positive reviews | 100.0% of reviews | — |
| Number of ratings | 2 — better | — |
| Update frequency | Every 4 months | Every 4 months |
| Ads | No — better | Yes |
| In-app purchases | No | No |
| Monetization | Free | — |
| Devices | iPhone, iPad | iPhone, iPad, iPod — better |
| Requires iOS | 17.6 | 15.0 — better |
| Further details — not scored | ||
| Size | 6 MB | 140 MB |
| Age rating | 4+ | 4+ |
| Developer | Rick Hutchinson | Hirobumi Onishi |
In-app purchases
PrimeXTime
No in-app purchases
Sosu der
No in-app purchases
