278 (two hundred [and] seventy-eight) is the natural number following 277 and preceding 279.

• 278 is an even composite number with 2 prime factors.^[1]
• 278 is equal to Φ(30). It is the sum of the totient function.^[2]
• 278 is a nontotient number which means that it is an even number that doesn't follow Euler's totient function.^[3]
• 278 is the smallest semiprime number that has an anagram that is also semiprime. The other number is 287.^[4]

• On October 29, 2011, April Mathis lifted the heaviest squat weight by a female at 278 kg in Orlando, Florida.^[5]
• On November 10, 1993, Tom Rodden received the Guinness World Record for shaving 278 people in one hour.^[6]
• On March 25, 2000, in Meadowhall Center, there were 278 human mannequins in the shopping center. They were in a total of 114 stores.^[7]
• On December 5, 2006, James Cripps received the Guinness World Record for the highest score in backwards bowling. The score was 278.^[8]

• The calendar years 278 AD and 278 BC.
• 278 is the number of several highways in Canada, Japan, and the United States.
• 278 Paulina is an asteroid in the asteroid belt. It was discovered by Johann Palisa in Vienna.^[9]