Identifying the Odd One Out
In the series 20, 24, 50, 122, and 170, we need to determine which number is different from the others based on specific criteria.

Analyzing the Numbers
- **20**: This number is even and can be expressed as the product of the prime factors 2 and 5 (2 x 2 x 5).
- **24**: This number is also even and can be expressed as 2 x 2 x 2 x 3 (2³ x 3).
- **50**: This number is even and can be expressed as 2 x 5 x 5 (2 x 5²).
- **122**: This number is even and can be expressed as 2 x 61 (2 x prime number).
- **170**: This number is even and can be expressed as 2 x 5 x 17 (2 x 5 x prime number).

Identifying the Unique Property
- All the numbers above are even. However, upon closer inspection, we can analyze their prime factors:
- **20**: 2, 5
- **24**: 2, 3
- **50**: 2, 5
- **122**: 2, 61
- **170**: 2, 5, 17

Conclusion
The odd one out is **24**.
- While all numbers are even, **24** is the only one that includes the factor **3** in its prime factorization. All others are products that consist solely of the prime number 2 combined with different prime numbers (5, 17, 61).
This distinction makes **24** unique in this set, highlighting how prime factorization can reveal underlying differences in seemingly similar numbers.