The power level of the card depends on the interpretation of the word "total". It is an adjective that describes Bilbo's willpower, attack and defence. If we take into account the entry Qualifiers in the rules reference document on p. 13 "If card text includes a qualifier followed by multiple terms, the qualifier applies to each item in the list, if it is applicable. For example, in the phrase “each ready character and attachment” the word “ready” applies to both “character” and “attachment.”, then The Lucky Number should be interpreted as "Add Bilbo Baggins' total willpower, [total] attack, and [total] defence...", which means Bilbo's stats are added separately to the other character's corresponding stats. If that was meant the other way, I guess the wording would be something like: "Add a total of Bilbo Baggins' willpower, attack, and defence...".
Overall, the Lucky number is an OK card, which you can do without in the Hobbit quests. If you include it, better take care also to include the means to boost Bilbo's stats. In that case i. e. Sting is a must.