Lucky number

Seas
Gables
Dwarves
Layer cake
Continents
Deadly sins
Days in a week
Witches in a coven
Sides on a heptagon
Musicians in a septet
Colors of the rainbow
Points on a sheriff's star
Notes on the musical scale
Periods on the periodic table
Wonders of the ancient world
Digits in a U.S. phone number

Years Lulu and Kiki have been together.

So far, no itch.