In his visualization, you can highlight any natural number (the normal numbers we count) on the number line and see how it relates to its fellow numbers.

Prime numbers are a central topic of study in math. Despite being an object of fascination for millennia, there are still a lot of unsolved problems involving primes.

Aurora Gallardo, The Extension of the Natural-Number Domain to the Integers in the Transition from Arithmetic to Algebra, Educational Studies in Mathematics, Vol. 49, No. 2 (2002), pp. 171-192 ...

An animated journey into the world of rational numbers! A fraction thief disrupts a number town, leading to a fun exploration of fractions, natural numbers, and mathematical concepts.