If your social security base in Lishui, Zhejiang is 20,500 yuan, the specific payment amount will vary depending on different types of insurance. In general, for basic pension insurance, the unit pays 2870 yuan (14% of 20,500), and the individual pays 1640 yuan (8% of 20,500); for basic medical insurance, the unit pays 1414.5 yuan (6.9% of 20,500), and the individual pays 410 yuan (2.0% of 20,500); for unemployment insurance, the unit pays 102.5 yuan (0.5% of 20,500), and the individual pays 102.5 yuan (0.5% of 20,500); for work-related injury insurance, the unit pays 92.25 yuan (0.45% of 20,500), and the individual doesn't pay; for disability insurance, the unit pays 307.5 yuan (1.5% of 20,500), and the individual doesn't pay. Here's a breakdown by each type of insurance:

1. Basic Pension Insurance: In Lishui, the unit contribution rate is 14% and the individual contribution rate is 8%. So for a base of 20,500 yuan, the unit's payment is ​
   ×14%=
   yuan, and the individual's payment is ​
   ×8%=
   yuan. Pension insurance is crucial for ensuring a stable income source for individuals after retirement.

2. Basic Medical Insurance: The unit contribution rate is 6.9%, and the individual contribution rate is 2.0%. Thus, the unit pays ​
   ×6.9%=1414.5
   yuan, and the individual pays ​
   ×2.0%=
   yuan. Medical insurance helps individuals cover medical expenses and reduces the financial burden of illness.

3. Unemployment Insurance: Both the unit and the individual have a contribution rate of 0.5%. So both the unit and the individual pay ​
   ×0.5%=102.5
   yuan. Unemployment insurance provides certain financial support to unemployed individuals during the period of unemployment.

4. Work - related Injury Insurance: The unit contribution rate is 0.45%, and individuals do not contribute. The unit pays ​
   ×0.45%=92.25
   yuan. This insurance is designed to protect employees in case of work - related injuries and provide compensation for medical treatment and lost work - time.

5. Disability Insurance: The unit contribution rate is 1.5%, and individuals do not contribute. The unit pays ​
   ×1.5%=307.5
   yuan. It aims to provide assistance and support for disabled individuals.

In summary, with a social security base of 20,500 yuan in Lishui, the total social security payment includes contributions from both the unit and the individual for different types of insurance. It's important to note that social security policies may be adjusted, so it's advisable to keep an eye on the latest announcements from the local social security department for the most accurate information.