21 in English
Nearby English Numbers
21 in Other Languages
About 21 in English
21 translates to twenty-one. The ordinal form — used for rankings, dates, and sequences — is twenty-first.
The number 21 is odd. In English-speaking environments, 21 is the kind of number you'll hear and need to use regularly, from market prices to building floor numbers.
Mastering numbers like 21 is one of the most practical skills when learning English. Unlike vocabulary that only applies in specific contexts, numbers come up constantly — in shops, on public transport, in conversations about time and money, and when meeting new people.
Learning Numbers in English
What makes English numbers challenging
English numbers seem simple but have hidden traps for learners. The teens (13-19) and tens (30-90) sound dangerously similar: "thirteen" vs "thirty," "fourteen" vs "forty." The stress pattern is the only difference, and it is easily lost in noisy environments or phone calls. Ordinals are largely irregular for the first few (first, second, third) before becoming regular (-th). Large numbers use a different grouping than many other languages — billion means a thousand million, not a million million as in some European countries.
Tips for learning English numbers
Pay close attention to the stress difference between teens and tens: thirTEEN has stress on the second syllable, while THIRty stresses the first. Practice with phone numbers and addresses since these are the most common real-world encounters. Learn the irregular ordinals (first through twelfth) as a group. For large numbers, get comfortable with the thousand-million-billion progression.