154

154 is a natural number that follows 153 and precedes 155. It is an even composite number and, more specifically, the product of three distinct primes: 2, 7, and 11. This makes 154 a squarefree, sphenic number.

Its divisors are 1, 2, 7, 11, 14, 22, 77, and 154, giving a total of eight divisors. The sum of these divisors is 288, and Euler’s totient function yields φ(154) = 60. The divisor count and the divisor sum reflect its factorization as 2 × 7 × 11.

154 is not a prime, nor a perfect square or cube. It is not expressible as a sum of two squares, because primes congruent to 3 modulo 4 (such as 7 and 11) appear to the first power in its factorization.

In different bases, 154 is written as 10011010 in binary and 0x9A in hexadecimal. In Roman numerals, it is CLIV.

Historically, the year AD 154 fell within the reign of Roman Emperor Antoninus Pius, placing it in the early second century of the Common Era.

As a compact mathematical object, 154 serves as an example of a small, squarefree, three-prime product with plainly verifiable divisor structure and standard base representations.