Names of 1981
| Nominal | 1981 |
| Cardinal | one thousand nine hundred eighty-one |
| Ordinal | 1,981st |
| This number as US currency | one thousand nine hundred eighty-one dollars |
| Is 1981 an odd number? | 1981 is an odd number |
| Is 1981 an even number? | 1981 is NOT an even number |
| Is 1981 a palindrome? | 1981 is NOT a palindrome number |
| Is 1981 a triangle number? | 1981 is NOT a triangle number |
1981 in other Bases
| Base 2 (Binary) | 111101111012 |
| Base 3 (Ternary) | 22011013 |
| Base 4 (Quaternary) | 1323314 |
| Base 5 (Quinary) | 304115 |
| Base 6 (Senary) | 131016 |
| Base 8 (Octal) | 36758 |
| Base 12 (Duodecimal) | 119112 |
| Base 16 (Hexadecimal) | 7BD16 |
| Base 20 (Vigesimal) | 4J120 |
Primes and Factors tests for 1981
| Is 1981 a Prime Number? | 1981 is NOT a prime |
| Is 1981 a perfect number? | 1981 is NOT a perfect number |
| Is 1981 a Mersenne Prime? | 1981 is NOT a Mersenne prime |
| Is 1981 a Fermat Prime? | 1981 is NOT a Fermat prime |
| Is 1981 a Fibonacci Prime? | 1981 is NOT a Fibonacci prime |
| Is 1981 a Partition Prime? | 1981 is NOT a Partition prime |
| Is 1981 a Pell Prime? | 1981 is NOT a Pell prime |
| Prime Factors | Prime factors of 1981 |
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1981 in other Numerals
| 1981 in Roman Numeral | MCMLXXXI |
| 1981 in Chinese Numeral | 壹仟玖佰捌拾壹 |
| 1981 in Egyptian Numeral | 𓆼𓍪𓎍𓏺 |
| 1981 in Babylonian Numeral |   |
Roots and stuff for 1981
| Is 1981 a square number? | 1981 is NOT a square number |
| Is 1981 a cube number? | 1981 is NOT a cube number |
| Square root of the number 1981 | 44.508426168536 |
| Cube root of the number 1981 | 12.559185985894 |
Recreational math for 1981
| Number 1981 reversed | 1891 |
| Sum of the digits | 19 |
| No of digits | 4 |