86 (number)
From Halbeeg, the open encyclopedia · Af-Soomaali
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86 is a natural number that follows 85 and precedes 87. It is a two-digit number in the decimal system, composed of 8 tens and 6 ones.
Like other intermediate numbers, 86 has practical applications in counting, measurement, and labeling—for example, in street numbers, tables, and book sections. It also has mathematical properties defined by its divisors.
Mathematical properties
86 is an even number, as it is divisible by 2 with no remainder. Its complete divisors are 1, 2, 43, and 86. It is therefore not a prime number, but rather a semiprime: 86 = 2 × 43. The two prime factors are 2 and 43.
The sum of its proper divisors—1, 2, and 43—equals 46. Since 46 is less than 86, the number is classified as deficient (its divisors sum to less than the number itself). In binary notation, 86 is written as 1010110.
Notation and numeral systems
In Roman numerals, 86 is written LXXXVI (50 + 10 + 10 + 10 + 5 + 1). In Somali, it is called siddeetan iyo lix.
Common uses
86 is used as an identifier in various contexts: historical years (for example, the year 86 CE or 1986), sports team numbers, and international telephone country codes in certain countries. Such use is purely nominal and carries no mathematical significance.