A rather dumb but fairly convenient tool for prime number related tasks (two of them), which I coded when I started to learn programming.
make
PREFIX=/your/prefix/ make installBy default it installs into ~/.usr/bin. This is rather idiosyncratic, but
doesn't require sudo and doesn't interfere with ~/.local.
If you don't need it on your PATH (why would you), then don't install and
just run ./primetool from the repository root after running make.
primetool -p NUMBER will find all prime numbers up to NUMBER and
print them to stdout (5 numbers on a line, duh).
primetool -f NUMBER will factorize the NUMBER and print the factorization
to stdout.