Code point
U+2284
Glyph appearance depends on your fonts.
U+2284
Sm2282 0338U+2284 NOT A SUBSET OF is a Unicode 16.0.0 character in the Math Symbol category. It belongs to the Mathematical Operators block.
Choose the representation you need, then copy its value.
U+2284
8836
⊄
⊄
⊄
E2 8A 84
2284
00002284
%E2%8A%84
\u2284
\u2284
\u2284
\2284