Function Return Help? attempt to concatenate string with function

The error is on line 29, trying to set the name so in another script it can tell if the part touched anything. I am purposely doing this on the client side. If there is anyway I can do this inside this script keeping it on the client, let me know. Here is my local script, inside a tool:

local gun = script.Parent
local ammo = game.ReplicatedStorage.NormalGunAmmo
local ActiveBullets = game.Workspace.ActiveBullets

local player = game.Players.LocalPlayer
local mouse = player:GetMouse()

local debounce = false
local count = 0

local function number()
	for i,v in pairs(ActiveBullets:GetChildren())do
		count = count+1
	end
	return count
end

gun.Activated:Connect(function()
	if debounce == false then
		debounce = true
		local bullet = ammo:Clone()
		bullet.CFrame = gun.Handle.CFrame
		
		local BodyVelocity = Instance.new("BodyVelocity",bullet)
		BodyVelocity.P = Vector3.new(10000,10000,10000)
		BodyVelocity.Velocity = mouse.Hit.LookVector * 100
		
		bullet.Parent = ActiveBullets
		bullet.Name = "Bullet"..number
		wait(.75)
		debounce = false
	end
end)

Error is in the title, and again, it occurs on line 29 trying to set the name, thanks!