| Nominal | 21000 |
| Cardinal | twenty-one thousand |
Cardinal twenty-one thousand | |
| Ordinal | 21,000th |
| Number of digits | 5 |
| Sum of digits | 3 |
| Product of digits | 0 |
| Number parity | Even |
| Prime factorization | 2 x 2 x 2 x 3 x 5 x 5 x 5 x 7 |
| Prime factorization in exponent form | 23 x 3 x 53 x 7 |
| Prime factors | 2, 3, 5, 7 |
| Number of distinct prime factors ω(n) | 4 |
| Total number of prime factors Ω(n) | 8 |
| Sum of prime factors | 17 |
| Product of prime factors | 210 |
| Is 21000 a prime number? | No |
| Is 21000 a semiprime number? | No |
| Is 21000 a Chen prime number? | No |
| Is 21000 a Mersenne prime number? | No |
| Is 21000 a Catalan number? | No |
| Is 21000 a Fibonacci number? | No |
| Is 21000 a Idoneal number? | No |
| Square of 21000 (n2) | 441000000 |
| Cube of 21000 (n3) | 9261000000000 |
| Square root of 21000 | 144.91376746189 |
| Natural Logarithm (ln) of 21000 | 9.9522777167056 |
| Decimal Logarithm (log) of 21000 | 4.3222192947339 |
| Sine of 21000 | 0.99971423939709 |
| Cosecant of 21000 | 1.0002858422854 |
| Cosine of 21000 | -0.023904801749939 |
| Secant of 21000 | -41.832599594872 |
| Tangent of 21000 | -41.82064548599 |
| Cotangent of 21000 | -0.023911634753103 |
| The spelling of 21000 in words is "twenty-one thousand", meaning that: |
| 21000 is not an aban number (as it contains the letter a) |
| 21000 is not an eban number (as it contains the letter e) |
| 21000 is an iban number (a number without the letter i) |
| 21000 is not an oban number (as it contains the letter o) |
| 21000 is not a tban number (as it contains the letter t) |
| 21000 is not an uban number (as it contains the letter u) |
| Bengali numerals | ২১০০০ |
| Eastern Arabic numerals | ٢١٬٠٠٠ |
| Hieroglyphs numeralsused in Ancient Egypt | 𓂭𓂭𓆼 |
| Khmer numerals | ២១០០០ |
| Japanese numerals | 二万千 |
| Roman numerals | n/a |
| Thai numerals | ๒๑๐๐๐ |
| Arabic | واحد و عشرون ألف |
| Croatian | dvadeset i jedna tisuća |
| Czech | dvacet jedna tisíc |
| Danish | en og tyve tusinde |
| Dutch | éénentwintigduizend |
| Estonian | akpe blaeve vɔ ɖekɛ |
| Faroese | tjúgoeitt tusin |
| Filipino | dalawáng pû’t isáng libó |
| Finnish | kaksikymmentäyksituhatta |
| French | vingt et un mille |
| Greek | είκοσι μία χίλιάδες |
| German | einundzwanzigtausend |
| Hebrew | עשרים ואחד אלף |
| Hindi | इक्कीस हज़ार |
| Hungarian | huszonegyezer |
| Icelandic | tuttugu og eitt þúsund |
| Indonesian | dua puluh satu ribu |
| Italian | ventunomila |
| Japanese | 二万千 |
| Korean | 이만 천 |
| Latvian | divdesmit viens tūkstoši |
| Lithuanian | dvidešimt vienas tūkstantis |
| Norwegian | tjueett tusen |
| Persian | بیست و یک هزار |
| Polish | dwadzieścia jeden tysięcy |
| Portuguese | vinte e um mil |
| Romanian | douăzeci şi una mii |
| Russian | двадцать одна тысяча |
| Serbian | двадесет и једна хиљада |
| Slovak | dvadsaťjedna tisíc |
| Slovene | dvaset ena tisuću |
| Spanish | veintiún mil |
| Swahili | elfu ishirini na moja |
| Swedish | tjugoentusen |
| Thai | สองหมื่นหนึ่งพัน |
| Turkish | yirmi bir bin |
| Ukrainian | двадцять одна тисяча |
| Vietnamese | hai mươi mốt nghìn |
| Number 21000 reversed | 00012 | |
| Unicode Character | U+5208 | 刈 |
| Unix Timestamp | Thu, 01 Jan 1970 05:50:00 +0000 | |