278 (two hundred [and] seventy-eight) is the natural number following 277 and preceding 279.
In mathematics 278 is an even composite number with 2 prime factors. 278 is equal to Φ(30). It is the sum of the totient function. 278 is a nontotient number which means that it is an even number that doesn't follow Euler's totient function. 278 is the smallest semiprime number that has an anagram that is also semiprime. The other number is 287.
See also List of highways numbered 278
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