# 21 in Words: How to Write 21 in English?

21 is spelled as twenty-one in English. It is a natural number following 20 and preceding 22. It’s odd (not divisible by 2) and composite (having more than two divisors) as well. Two-digit numbers like 21 are typically expressed by combining the names of the tens and ones digits.  For example, “twenty” signifies the two (tens place), and “one” signifies the one (ones place). This written form is important for clear communication in various contexts, such as specifying a monetary amount (e.g., “twenty-one rupees”).

## 21 in Words in English

In written form, 21 is expressed as “twenty-one.” Here, the tens digit (2) is represented by “twenty,” and the one’s digit (1) is represented by “one”. It holds many important properties. Some important properties related to number 21 are stated below:

• 21 is classified as a natural number. Natural numbers are the fundamental counting numbers, representing positive whole quantities (1, 2, 3, etc.).
• 21 is classified as an odd number. Odd numbers are not divisible by 2 without a remainder. In contrast, even numbers are perfectly divisible by 2.
• A perfect square is a number obtained by squaring an integer (e.g., 4 is a perfect square because 2 x 2 = 4). 21 is not a perfect square as it cannot be obtained by squaring any whole number.
• A perfect cube is a number obtained by cubing an integer (e.g., 8 is a perfect cube because 2 x 2 x 2 = 8). 21 is not a perfect cube either.
• A prime number is a natural number greater than 1 that has exactly two distinct positive divisors: 1 and itself (e.g., 7 is prime). 21 fails this criterion. It has more than two divisors (1, 3, 7, and 21). Therefore, 21 is a composite number. Composite numbers are any natural numbers greater than 1 that are not prime.

## How to Convert 21 in Words?

21 is a number with a specific written form (“twenty-one”) derived from its place values. Let’s convert  21 in words in English:

• Numbers with two digits are expressed by combining the names for their tens and ones place values.
• The digit in the tens place (here, “2”) is represented by its corresponding word, “twenty.”
• The digit in the one’s place (here, “1”) is represented by its corresponding word, “one.”
•  We combine the tens and ones place representations with a hyphen: “twenty-one.”
• Therefore: 21 is written in words as “twenty-one.”

Must Read:20 in Words: How to Spell in 20 in English?

## Rules to Write Numbers in English

Numbers can be tricky in English. Here we have mentioned simple steps to help you write them effectively:

• Small Numbers (1-9): Spell out numbers one through nine in most contexts (e.g., five apples, seven days).
• Larger Numbers (10+): Use numerals (numbers as digits) for numbers ten and above (e.g., 12 o’clock, 35 kilometres).
• Sentence Starters: Always spell out a number that begins a sentence, regardless of size (e.g., Twenty-three guests arrived).
• Numbers in Phrases: Certain common phrases might use spelt-out numbers even for larger values (e.g., a hundred years, two dozen eggs).

## Facts of Number 21

Look beyond the number.21 holds significance in many fields. From science to technology, from sports to games, here we have stated some interesting facts related to number 21:

• 21 is the atomic number of Scandium, an element.
• In some countries, 21 marks the legal age for activities like drinking, gambling, or purchasing firearms.
• 21 is significant in some sports – the number of points needed to win in 3×3 basketball or the squad size in AFL Women’s.
• The number 21 is associated with card games like Blackjack where achieving 21 points wins.

Must Read: 27 in Words: How to Write 27 in English ?

## 1 to 21 Numbers in Words

A number names chart (1-21 can be a helpful tool for children learning to spell numbers).  They can practice by calling out numbers they see around them, making learning fun and interactive.

## FAQs

How do you write 21 in words?

21 in words is written as twenty-one.

How do you write 21 to 30 in words?

21 to 30 in words: Twenty-one, twenty-two, twenty-three, twenty-four, twenty-five, twenty-six, twenty-seven, twenty-eight, twenty-nine, thirty.

How to write 22 in words?

22 in words is written as twenty-two.

How do you spell 21 rupees?

21 rupees is spelled as twenty-one rupees

This was all about the “21 in Words”. For more such informative blogs, check out our Study Material Section, or you can learn more about us by visiting our  Indian exams page.