催 means to hold, organize (an event) and is a JLPT N1 kanji. It has 13 strokes and uses the person (side) radical (亻).
Stroke order · 13 strokes
On'yomi (音読み)
サイ
Kun'yomi (訓読み)
もよう(す)、もよお(す)
Radical
亻 · person (side)
Strokes
13
How to remember 催
A person (亻) calling out and gathering others like a bird on a hill — organizing an event. 開催 is the word used for オリンピック開催 (holding the Olympics); 催し means an event.