You type in a number and it presents you with loads of facts about that number, breaking it down into it’s prime factors and some scales. It’s lovely. Try it yourself. Here’s the page for 2048.
Quick starter idea (after showing students this website):
56
Give me some facts about this number.
You could use this often, changing the number every time.
Quick investigation idea: What is the best number? Explain why. Give reasons.