2 (number)

2 was a number.

7 was not divisible by 2. (PROSE: And Then Again)

The Ux were a duo-species, meaning there were always only two of them. (TV: The Battle of Ranskoor Av Kolos)

The Boneless came from a universe with only two dimensions. (TV: Flatline)

The Twelfth Doctor once told Bill that "eleven plus two" was an anagram of "twelve plus one", to which Bill responded that both of these were equal to 13. (COMIC: Harvest of the Daleks)

Humanoids had two arms, and were bipedal, meaning they had two legs, and binocular, meaning they had two eyes. (TV: Kinda) They also had two ears. (TV: Rose) The resulting symmetry played a large part in attractiveness. (TV: World Enough and Time)

Time Lords had a binary vascular system, meaning they also had two hearts. (TV: Spearhead from Space, et al.) On discovering the Tenth Doctor had two hearts, Jackie Tyler wondered if there was anything else he had two of. (TV: The Christmas Invasion)

The Horrorkons had two heads per body, (COMIC: Monsters of Gurnian) as did the Terrorkons (COMIC: Impasse) and the Aplans. (TV: The Time of Angels)

Planets with two moons included Colony 34, (AUDIO: LIVE 34) Crimson Heart, (TV: Death of the Doctor) Funderell, (AUDIO: The Skin of the Sleek) Gallifrey, (PROSE: Cat's Cradle: Time's Crucible) Juno 10, (AUDIO: Penny Wise, Pound Foolish) Liberius, (PROSE: First Born) Mendorax Dellora, (TV: The Husbands of River Song) Skaro, (AUDIO: Davros, Purity) Symbios (AUDIO: The Crimes of Thomas Brewster) and Trenzalore. (PROSE: Strangers in the Outland)

During the COVID-19 pandemic, humans had to stand at least two metres away from each other to prevent passing on the virus. (PROSE: 8.46)

The countdown towards the Ninth Doctor's eviction on Big Brother counted from 6 to 0, going through 5, 4, 3, 2, and 1. (TV: Bad Wolf)

In an emergency transmission sent by the TARDIS, the Thirteenth Doctor listed 5 things that she did in any worrying situation. The second was telling jokes, especially bad ones, which she claimed to be 'brilliant' at. (WC: Message from the Doctor)

"ChatGuest1" repaired his broken radio in Pete's World by pressing the FM button twice. This solution was found by the readers of Defending the Earth! from the Doctor's universe, after going onto www.internationalelectromatics.co.uk and troubleshooting the problem with the IE ATSS. (GAME: Cybus Spy)

Behind the scenes
Though unremarked in PROSE: Daisy Chain, 2 is also the third number in the Fibonacci sequence. Also, unremarked in AUDIO: The Haunting is that 2 is a prime number.