20,991 in words
20,991
twenty thousand nine hundred ninety-one
20,991 is written twenty thousand nine hundred ninety-one.
Ways to write it
- As an ordinal
- twenty thousand nine hundred ninety-first
- Expanded form
- 20,000 + 900 + 90 + 1
Place value
| Place | Digit | Value |
|---|---|---|
| ten thousands | 2 | 20,000 |
| thousands | 0 | 0 |
| hundreds | 9 | 900 |
| tens | 9 | 90 |
| ones | 1 | 1 |
Number facts
- Even or odd
- Odd
- Prime or composite
- Composite
- Factors
- 1, 3, 6,997 and 20,991 (4 factors)
- First 10 multiples
- 20,991, 41,982, 62,973, 83,964, 104,955, 125,946, 146,937, 167,928, 188,919, 209,910
- Square
- 20,991 × 20,991 = 440,622,081
- Square root
- ≈ 144.88
- Sum of the digits
- 2 + 0 + 9 + 9 + 1 = 21
- Rounded to the nearest 10
- 20,990
- Rounded to the nearest 100
- 21,000
- Rounded to the nearest 1000
- 21,000
- Number before
- 20,990
- Number after
- 20,992
- In binary
101000111111111
Quick check
What number comes just after 20,991?
Show the answer
20,992
Is 20,991 even or odd?
Show the answer
Odd
What is 20,991 + 10?
Show the answer
21,001
Practise with a game
Factors, Multiples & Primes
Multiples, factors, prime numbers, square numbers and prime factors.
Number Patterns
Find the missing number in a sequence.Frequently asked questions
How do you write 20,991 in words?
20,991 is written "twenty thousand nine hundred ninety-one".
Is 20,991 a prime number?
No. 20,991 is a composite number, because it has more than two factors.
What are the factors of 20,991?
The factors of 20,991 are 1, 3, 6,997 and 20,991.