# Primality vs Momentous Clock

The clearest difference is update cadence: Momentous Clock at every 6 days against Primality's every 2 months. Primality's advantage is ratings volume (24 vs 2) and iOS requirement (13.2 vs 15.1). 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 Momentous Clock. That said, the two scores are not equally well evidenced: Primality has 24 ratings behind it against 2, so its average is the more settled of the two.

Primality ships an update every 2 months, Momentous Clock every 6 days. The most recent releases landed on September 27, 2026 and October 3, 2026 respectively.

## The numbers

| Metric | Primality | Momentous Clock |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.9 (24 ratings)](https://appshunter.io/ios/app/primality/id1516003672/reviews) | **[5.0 (2 ratings)](https://appshunter.io/ios/app/momentous-clock/id1608715857/reviews)** |
| Number of ratings | **24** | 2 |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 2 months | **Every 6 days** |
| Monetization | Free | Free |
| Size | 1 MB | 24 MB |
| Requires iOS | **13.2** | 15.1 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Bruce Schechter](https://appshunter.io/developer/1515359087) | [Tutukain Software, LLC](https://appshunter.io/developer/1608715859) |

## 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


### Momentous Clock

[App page](https://appshunter.io/ios/app/momentous-clock/id1608715857)

This app transforms your device's clock into a dynamic display of mathematical properties and number theory facts for the current time. It optionally reveals personal number connections from your contacts, all processed securely on your device.

**Highlights:** Computes mathematical properties of time, Surfaces number theory facts, Displays time on 16-segment LED screens, Finds personal number connections in contacts, On-device contact matching, Works via Catalyst on Mac

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Primality free?

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

### Is Momentous Clock free?

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

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

Momentous Clock is rated higher. Primality averages 4.9 out of 5 from 24 ratings, while Momentous Clock averages 5.0 from 2 ratings.

### Do Primality or Momentous Clock have ads?

Neither Primality nor Momentous Clock shows ads.

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

Primality ships an update every 2 months, and Momentous Clock every 6 days. Most recently, Primality was updated on September 27, 2026 and Momentous Clock on October 3, 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.*