# Is it Prime? vs Cool Penguin Clock

The clearest difference is in-app purchases: Is it Prime? at none against Cool Penguin Clock's 1. Is it Prime? also leads on ads (none vs shown). Cool Penguin Clock's advantage is update cadence (every 3 weeks vs every 74 months) and iOS requirement (12.0 vs 15.0). On price and device support there is nothing between them.

Both are free to download. Cool Penguin Clock sells 1 one-off in-app purchase. Is it Prime? asks for nothing beyond the download.

Is it Prime? ships an update every 74 months, Cool Penguin Clock every 3 weeks. The most recent releases landed on October 11, 2026 and September 30, 2026 respectively.

## The numbers

| Metric | Is it Prime? | Cool Penguin Clock |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[3.2 (5 ratings)](https://appshunter.io/ios/app/is-it-prime/id326095651/reviews)** | — |
| Number of ratings | **5** | — |
| Positive reviews | 71.4% of reviews | — |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 74 months | **Every 3 weeks** |
| Monetization | Free | — |
| Size | 1 MB | 27 MB |
| Requires iOS | 15.0 | **12.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Wismar](https://appshunter.io/developer/307757950) | [Mihoko Araki](https://appshunter.io/developer/1476136915) |

## What reviewers say

### Is it Prime?

[App page](https://appshunter.io/ios/app/is-it-prime/id326095651)

Enter any number to instantly determine if it is a prime number or not. This straightforward utility provides a quick answer to your mathematical curiosity.

**Highlights:** Prime number identification, Simple number input, Instant yes/no results

**Features:** macOS Compatibility

**In-app purchases:** none


### Cool Penguin Clock

[App page](https://appshunter.io/ios/app/cool-penguin-clock/id6453357439)

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Penguin Clock with no ads | $1.99 | one-time |


## Frequently asked questions

### Is Is it Prime? free?

Is it Prime? is free to download, with no in-app purchases.

### Is Cool Penguin Clock free?

Cool Penguin Clock is free to download, with in-app purchases available.

### Do Is it Prime? or Cool Penguin Clock have ads?

Cool Penguin Clock shows ads; Is it Prime? does not.

### Which is updated more often, Is it Prime? or Cool Penguin Clock?

Is it Prime? ships an update every 74 months, and Cool Penguin Clock every 3 weeks. Most recently, Is it Prime? was updated on October 11, 2026 and Cool Penguin Clock on September 30, 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.*