Wow - 21,000 is a lot of extra people to fit into our little city. But bring it on, I say.
The Lions tour is just weeks away, with the side and their huge army of supporters due to arrive in Rotorua for a match against the Maori All Blacks on Saturday, June 17.
I wasn't here for the 2005 Lions tour, but by all accounts it was an exciting time in Rotorua. And this year is expected to be even bigger.
With Rotorua having so much to offer visitors, aside from the rugby, it's likely many will spend more than just the one night in town. Accommodation providers, restaurant and bar owners and retailers will be rubbing their hands together in glee in anticipation of what is bound to be one of their biggest couple of days in years.
Even if you are not a rugby fan, there will be no escaping the fans in and around Rotorua.
The good news is they are generally a jovial bunch - for many Lions supporters this will be a trip they have been dreaming of and saving for for years. For many it will be their first time to New Zealand, a special place for these hard-core rugby fans.
So I hope Rotorua and its citizens pull out all the stops to make them feel welcome. Sure, there may be little inconveniences - the roads will be busy and the queue for a beer at your local may suddenly get a lot bigger.
But these are fleeting and small things that will be outweighed by what the Lions and their supporters will bring to our city - a buzz, an energy, a desire to meet us and a shared love of the sport and all it brings.
It's a chance to show off our city at its finest, sending 21,000 people home to Britain and Ireland with nothing but good things to say about Rotorua.
I can't wait.