Names of 1821
| Nominal | 1821 |
| Cardinal | one thousand eight hundred twenty-one |
| Ordinal | 1,821st |
| This number as US currency | one thousand eight hundred twenty-one dollars |
| Is 1821 an odd number? | 1821 is an odd number |
| Is 1821 an even number? | 1821 is NOT an even number |
| Is 1821 a palindrome? | 1821 is NOT a palindrome number |
| Is 1821 a triangle number? | 1821 is NOT a triangle number |
1821 in other Bases
| Base 2 (Binary) | 111000111012 |
| Base 3 (Ternary) | 21111103 |
| Base 4 (Quaternary) | 1301314 |
| Base 5 (Quinary) | 242415 |
| Base 6 (Senary) | 122336 |
| Base 8 (Octal) | 34358 |
| Base 12 (Duodecimal) | 107912 |
| Base 16 (Hexadecimal) | 71D16 |
| Base 20 (Vigesimal) | 4B120 |
Primes and Factors tests for 1821
| Is 1821 a Prime Number? | 1821 is NOT a prime |
| Is 1821 a perfect number? | 1821 is NOT a perfect number |
| Is 1821 a Mersenne Prime? | 1821 is NOT a Mersenne prime |
| Is 1821 a Fermat Prime? | 1821 is NOT a Fermat prime |
| Is 1821 a Fibonacci Prime? | 1821 is NOT a Fibonacci prime |
| Is 1821 a Partition Prime? | 1821 is NOT a Partition prime |
| Is 1821 a Pell Prime? | 1821 is NOT a Pell prime |
| Prime Factors | Prime factors of 1821 |
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1821 in other Numerals
| 1821 in Roman Numeral | MDCCCXXI |
| 1821 in Chinese Numeral | 壹仟捌佰貳拾壹 |
| 1821 in Egyptian Numeral | 𓆼𓍩𓎇𓏺 |
| 1821 in Babylonian Numeral |   |
Roots and stuff for 1821
| Is 1821 a square number? | 1821 is NOT a square number |
| Is 1821 a cube number? | 1821 is NOT a cube number |
| Square root of the number 1821 | 42.673176586704 |
| Cube root of the number 1821 | 12.211527222018 |
Recreational math for 1821
| Number 1821 reversed | 1281 |
| Sum of the digits | 12 |
| No of digits | 4 |