I Built a Python Library That Classifies 3000+ Number Types — At 15

Aratrik Ghosh — Sat, 18 Apr 2026 17:26:29 +0000

I'm 15, in Class 10, and I just shipped my first Python package to PyPI. Here's what I built and why nobody else had done it.

The Problem

There are tons of Python libraries for number computation — factoring, GCDs, prime generation. But none of them answer this:

What type of number is this?

Not just "is it prime?" — I mean every named mathematical category it belongs to.

import numclassify as nc

nc.get_true_properties(1729)
# ['taxicab', 'carmichael', 'zeisel', 'odd', 'deficient', 'squarefree']

1729 is the Hardy-Ramanujan number — smallest expressible as sum of two cubes in two different ways. It's also a Carmichael number and a Zeisel number. Most people only know one of those facts. numclassify knows all of them instantly.

What It Does

3000+ named number types, 10 categories, zero dependencies, Python 3.8–3.13.

Category	Count	Examples
Polygonal	998	Triangular, Square, Pentagonal…
Centered Polygonal	998	Centered Triangular, Centered Hexagonal…
Prime families	41	Twin, Mersenne, Sophie Germain…
Digital invariants	10	Armstrong, Harshad, Happy, Disarium…
Divisor-based	27	Perfect, Abundant, Weird, Amicable…
Sequences	15	Fibonacci, Lucas, Catalan, Bell…
Powers	13	Perfect Square, Taxicab…
Number theory	14	Evil, Carmichael, Keith…

Quick Examples

import numclassify as nc

# Boolean checks
nc.is_prime(17)         # True
nc.is_armstrong(153)    # True
nc.is_perfect(28)       # True

# All true properties
nc.get_true_properties(153)
# ['armstrong', 'harshad', 'triangular', 'abundant']

# Search a range
nc.find_in_range(nc.is_armstrong, 1, 10000)
# [1, 2, 3, 4, 5, 6, 7, 8, 9, 153, 370, 371, 407, 1634, 8208, 9474]

# What's the most "special" number between 1 and 1000?
nc.most_special_in_range(1, 1000)

CLI

$ numclassify check 1729
taxicab        ✓
carmichael     ✓
zeisel         ✓
odd            ✓

$ numclassify find armstrong --limit 5
1, 2, 3, 153, 370

$ numclassify info armstrong
Name:        armstrong
Category:    digital_invariants
Description: Sum of digits each raised to power of digit count
Examples:    1, 2, 3, 153, 370, 371, 407

Install

pip install numclassify

GitHub: https://github.com/aratrikghosh2011-tech/numclassify
PyPI: https://pypi.org/project/numclassify/

Built this because I was studying number theory for competitive maths and kept writing the same classification checks over and over. Figured if I needed it, others did too.

Feedback welcome — especially if you find a number type I'm missing.

DEV Community: Aratrik Ghosh

I Built a Python Library That Classifies 3000+ Number Types — At 15

The Problem

What It Does

Quick Examples

CLI

Install