Names of 18991
| Nominal | 18991 |
| Cardinal | eighteen thousand nine hundred ninety-one |
| Ordinal | 18,991st |
| This number as US currency | eighteen thousand nine hundred ninety-one dollars |
| Is 18991 an odd number? | 18991 is an odd number |
| Is 18991 an even number? | 18991 is NOT an even number |
| Is 18991 a palindrome? | 18991 is NOT a palindrome number |
| Is 18991 a triangle number? | 18991 is NOT a triangle number |
18991 in other Bases
| Base 2 (Binary) | 1001010001011112 |
| Base 3 (Ternary) | 2220011013 |
| Base 4 (Quaternary) | 102202334 |
| Base 5 (Quinary) | 11014315 |
| Base 6 (Senary) | 2235316 |
| Base 8 (Octal) | 450578 |
| Base 12 (Duodecimal) | ABA712 |
| Base 16 (Hexadecimal) | 4A2F16 |
| Base 20 (Vigesimal) | 279B20 |
Primes and Factors tests for 18991
| Is 18991 a Prime Number? | 18991 is NOT a prime |
| Is 18991 a perfect number? | 18991 is NOT a perfect number |
| Is 18991 a Mersenne Prime? | 18991 is NOT a Mersenne prime |
| Is 18991 a Fermat Prime? | 18991 is NOT a Fermat prime |
| Is 18991 a Fibonacci Prime? | 18991 is NOT a Fibonacci prime |
| Is 18991 a Partition Prime? | 18991 is NOT a Partition prime |
| Is 18991 a Pell Prime? | 18991 is NOT a Pell prime |
| Prime Factors | Prime factors of 18991 |
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18991 in other Numerals
| 18991 in Roman Numeral | XVMMMCMXCI |
| 18991 in Chinese Numeral | 壹萬捌仟玖佰玖拾壹 |
| 18991 in Egyptian Numeral | 𓂭𓇃𓍪𓎎𓏺 |
| 18991 in Babylonian Numeral |    |
Roots and stuff for 18991
| Is 18991 a square number? | 18991 is NOT a square number |
| Is 18991 a cube number? | 18991 is NOT a cube number |
| Square root of the number 18991 | 137.80783722271 |
| Cube root of the number 18991 | 26.679802556031 |
Recreational math for 18991
| Number 18991 reversed | 19981 |
| Sum of the digits | 28 |
| No of digits | 5 |