This character is a Decimal Number and is commonly used, that is, in no specific script. The codepoint has the decimal value 9.
The glyph is not a composition. Its East Asian Width is narrow. In bidirectional text it is written as European number from left to right. When changing direction it is not mirrored. This number joins with other adjacent letters and numbers to form a word. U+0039 forms a number with similar characters, which prevents a line break inside it. The glyph can be confused with 26 other glyphs.
This character is designated as an emoji. It will be rendered as monochrome character on conforming platforms. To enable colorful emoji display, you can combine it with Glyph for U+FE0FVariation Selector-16: 9️ See the Emojipedia for more details on this character’s emoji properties.
The Wikipedia has the following information about this codepoint:
9 (nine) is the natural number following 8 and preceding 10.