1)   Prime Number Calculator 4.6.1
Calculate the prime numbers between two limits. It uses a deterministic test and uses the Sieve of Eratophenes logic. Recommended on The Math Forum @ Drexel (University) for Middle School, High School and College, ages 6+. 99¢ only.

 2)   Factor Calculator 5.6.2
Calculate the factors of any number with a single click. Small application window allows simultaneous use with Word, Outlook, Excel, etc.. Recommended on The Math Forum @ Drexel (University) for Middle School, High School and College, ages 6+. 99¢

 3)   Factorizer 9.21
A program to find prime numbers and pairs of primes, to decompose numbers into their prime constituents, to find all factors of any positive integer up to 2,147,483,645, and to plot Erdos-Kac and Palmen Color histograms.

 4)   Primality Tester 5.3.2
Test any number for primality with a single click. It uses a deterministic test and uses the Sieve of Eratophenes logic. Recommended on The Math Forum @ Drexel (University) for Middle School, High School and College, ages 6+. 99¢ only.

 5)   Prime Number Spiral 6.67
The Prime Number Spiral (a.k.a. the Ulam Spiral) is formed by marking the prime numbers in a spiral arrangement of the natural numbers. This is software is for exploring the Prime Number Spiral.

 6)   CFB Primes 2.0
CFB Primes is an optimised PalmOS program which can find the prime factors and closest primes of any integer up to one billion (US) in a few seconds or less. The standard edit menu allows you to make use of the results in other applications.