# PrimeXTime vs Sosu der

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.

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.

## The numbers

| Metric | PrimeXTime | Sosu der |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (2 ratings)](https://appshunter.io/ios/app/primextime/id1253706544/reviews)** | — |
| Number of ratings | **2** | — |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | **No** | Yes |
| Update frequency | Every 4 months | Every 4 months |
| Monetization | Free | — |
| Size | 6 MB | 140 MB |
| Requires iOS | 17.6 | **15.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Rick Hutchinson](https://appshunter.io/developer/1253697991) | [Hirobumi Onishi](https://appshunter.io/developer/1740115066) |

## What reviewers say

### PrimeXTime

[App page](https://appshunter.io/ios/app/primextime/id1253706544)

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.

**Highlights:** Number division by primes, Strategic bumping mechanic, Goal to reduce number to 1, Brain exercise gameplay, Simple, intuitive interface

**Features:** macOS Compatibility

**In-app purchases:** none


### Sosu der

[App page](https://appshunter.io/ios/app/sosu-der/id6483364985)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is PrimeXTime free?

PrimeXTime is free to download, with no in-app purchases.

### Is Sosu der free?

Sosu der is free to download, with no in-app purchases.

### Do PrimeXTime or Sosu der have ads?

Sosu der shows ads; PrimeXTime does not.

### Which is updated more often, PrimeXTime or Sosu der?

PrimeXTime ships an update every 4 months, and Sosu der every 4 months. Most recently, PrimeXTime was updated on June 1, 2026 and Sosu der on September 13, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*