Doug's Zillion

Doug's Zillion is equal to 10^1722, also known as a treseptuaginticentillion'''. 'This number originates from an episode of the Nickelodeon animated cartoon Doug, titled Doug's Mail Order Mania''. In this episode, the title character enters a fraudulent sweepstakes which purports to offer this amount in US$ as a prize. Said number is repeatedly referred to as a "zillion" dollars.

Notably, the number is written out in full in the episode, taking up several pages of paper. Although it's impossible to see the whole thing at once, the size of the number can be determined by counting the number of zeros on one visible page, multiplying it by the total number of zero-filled pages, and adding the 21 zeros on the first page.

This is quite possibly the largest number ever explicitly referenced in a cartoon.