specialnumber
nounUK /ˈspɛʃəl ˈnʌmbə/
US /ˈspɛʃəl ˈnʌmbər/
A special number is a number that is important or fun to you.
Seven is my special number because it is my birthday.
OTHER MEANINGS
2. A number that has a unique or interesting mathematical property.
Prime numbers are special numbers that can only be divided by one and themselves.
3. A number used as a code or password to unlock something.
She typed her special number into the lock to open the door.
4. A number that stands out in a game or story.
In the story, the special number three opened the secret gate.