# Primality vs Eternal Clock

The clearest difference is update cadence: Eternal Clock at weekly against Primality's every 2 months. Primality's advantage is ratings volume (24 vs 1). On price, rating, ads and in-app purchases there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

On the App Store both sit at effectively the same score — 4.9 for Primality against 5.0 for Eternal Clock. That said, the two scores are not equally well evidenced: Primality has 24 ratings behind it against 1, so its average is the more settled of the two.

Primality ships an update every 2 months, Eternal Clock weekly. The most recent releases landed on October 13, 2026 and October 4, 2026 respectively.

## The numbers

| Metric | Primality | Eternal Clock |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.9 (24 ratings)](https://appshunter.io/ios/app/primality/id1516003672/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/eternal-clock/id6752602424/reviews)** |
| Number of ratings | **24** | 1 |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 2 months | **Weekly** |
| Monetization | Free | Free |
| Size | 1 MB | 23 MB |
| Requires iOS | 13.2 | **12.0** |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Bruce Schechter](https://appshunter.io/developer/1515359087) | [Daehyeon Shin](https://appshunter.io/developer/1698890567) |

## What reviewers say

### Primality

[App page](https://appshunter.io/ios/app/primality/id1516003672)

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.

**Highlights:** Primality testing, Prime factorization, Prime ordinality calculation, Large integer support (up to 999,999,999,999), Clean and simple interface

**Features:** macOS Compatibility

**In-app purchases:** none


### Eternal Clock

[App page](https://appshunter.io/ios/app/eternal-clock/id6752602424)

A minimalist digital clock that displays the time with no distractions. It offers a clean interface with subtle visual cues like a sun, moon, or mealtime hints, all without ads, data collection, or notifications.

**Highlights:** Ad-free experience, No data collection, No push notifications, Minimalist interface, Subtle visual cues (sun, moon, food), No settings or permissions required

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

**In-app purchases:** none


## Frequently asked questions

### Is Primality free?

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

### Is Eternal Clock free?

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

### Which has better reviews, Primality or Eternal Clock?

Eternal Clock is rated higher. Primality averages 4.9 out of 5 from 24 ratings, while Eternal Clock averages 5.0 from 1 ratings.

### Do Primality or Eternal Clock have ads?

Neither Primality nor Eternal Clock shows ads.

### Which is updated more often, Primality or Eternal Clock?

Primality ships an update every 2 months, and Eternal Clock weekly. Most recently, Primality was updated on October 13, 2026 and Eternal Clock on October 4, 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.*