The exact factorial of 21 is:

51090942171709440000

📌 Number of digits in the exact factorial of 21! = 20.

Approximately, the value of 21! can also be written as 5.109094217 E+19.

How to calculate 21!

The formula for finding the factorial of a number is:

n! = n × (n-1) × (n-2) × … × 2 × 1

The same formula can also be written in terms of PI product notation as:

Factorial Formula

So, by definition, 21! is calculated as:

21 × 20 × 19 × … × 2 × 1

Also see:

Frequently asked questions

Here are some frequently asked questions about factorial of 21:

How many digits are there in the exact value of 21!?

There are 20 digits in the exact value of 21!.

What is the value of 21 factorial in terms of E?

The value of 21! in terms of E is 5.109094217 E+19.

What are the uses of factorials?

According to Wikipedia:

In mathematical analysis, factorials are used in power series for the exponential function and other functions, and they also have applications in algebra, number theory, probability theory, and computer science.