154 (number)
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154 is a natural number that follows 153 and precedes 155. It is an even number, meaning it is divisible by 2 with no remainder. It is also a composite number, meaning it has divisors other than 1 and itself.
The prime factorization of 154 is 2 × 7 × 11. Because it is the product of three distinct primes, each appearing exactly once, 154 is known as a sphenic number. Its divisors are 1, 2, 7, 11, 14, 22, 77, and 154.
Mathematical properties
The sum of its proper divisors (those excluding the number itself) is 1 + 2 + 7 + 11 + 14 + 22 + 77 = 134. Since 134 is less than 154, this number is classified as deficient, meaning the sum of its proper divisors is less than the number itself.
154 is one of the nonagonal numbers, which are numbers generated by the formula n(7n − 5)/2. When n equals 7, the result is 154. These numbers represent the count of dots that can be arranged in a nested nonagon pattern.
Representation in number systems
In binary, 154 is written as 10011010. In hexadecimal, it is 9A. In Roman numerals, 154 is written as CLIV.
Other uses
Like other small numbers, 154 is used in various standard notation systems: year numbers (the year 154 CE and 154 BCE), road designations, legal codes and statutes, and list numbering. The meaning of such uses depends on the notation system employed and is unrelated to the mathematical properties of the number.