Keycap: 4

Unicode lists 4️⃣ Keycap: 4 among the keycap numbers in the Symbols group. It usually appears in messages about 4, four and keycap.

4️⃣ works in messages, comments, captions and profile names. On SmileyZone it is filed under Numbers and Letters. It joined the standard with Emoji 0.6 in 2010, so support on current devices is reliable. Its code point is U+0034 U+20E3.

• 4️⃣ on its own already flags the topic: 4.
• Fits messages about 4, four and keycap.
• Often seen near 3️⃣ Keycap: 3, 2️⃣ Keycap: 2 and 5️⃣ Keycap: 5.

Easy to mix up with 3️⃣ Keycap: 3, 2️⃣ Keycap: 2 or 5️⃣ Keycap: 5. They sit in the same Unicode subgroup and look similar at small sizes, so it is worth checking the name before sending.