178 (number)
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178 is a natural number between 177 and 179. It is an even number, being divisible by two. In base 10, it comprises one hundred, seven tens, and three units.
In number theory, 178 is a composite number and not prime. Its divisors are 1, 2, 89, and 178.
Mathematical properties
The prime factorization is 178 = 2 × 89. Since both prime factors are distinct, 178 is a semiprime. Because one of its factors is 2, it is an even number and not divisible by 4.
The sum of all its divisors is 1 + 2 + 89 + 178 = 270. The aliquot sum, which is the sum of its proper divisors (excluding the number itself), is 1 + 2 + 89 = 92. Since 92 is less than 178, it is a deficient number.
Euler's totient function φ(178), which counts integers less than 178 that share no common factor with it, equals (2−1) × (89−1) = 88.
Other representations
In binary, 178 is represented as 10110010. In Roman numerals it is written CLXXVIII. It can also be expressed as the sum of two squares: 178 = 13² + 3² = 169 + 9.