Names of 19991
| Nominal | 19991 |
| Cardinal | nineteen thousand nine hundred ninety-one |
| Ordinal | 19,991st |
| This number as US currency | nineteen thousand nine hundred ninety-one dollars |
| Is 19991 an odd number? | 19991 is an odd number |
| Is 19991 an even number? | 19991 is NOT an even number |
| Is 19991 a palindrome? | 19991 is a palindrome number |
| Is 19991 a triangle number? | 19991 is NOT a triangle number |
19991 in other Bases
| Base 2 (Binary) | 1001110000101112 |
| Base 3 (Ternary) | 10001021023 |
| Base 4 (Quaternary) | 103201134 |
| Base 5 (Quinary) | 11144315 |
| Base 6 (Senary) | 2323156 |
| Base 8 (Octal) | 470278 |
| Base 12 (Duodecimal) | B69B12 |
| Base 16 (Hexadecimal) | 4E1716 |
| Base 20 (Vigesimal) | 29JB20 |
Primes and Factors tests for 19991
| Is 19991 a Prime Number? | 19991 is a prime |
| Is 19991 a perfect number? | 19991 is NOT a perfect number |
| Is 19991 a Mersenne Prime? | 19991 is NOT a Mersenne prime |
| Is 19991 a Fermat Prime? | 19991 is NOT a Fermat prime |
| Is 19991 a Fibonacci Prime? | 19991 is NOT a Fibonacci prime |
| Is 19991 a Partition Prime? | 19991 is NOT a Partition prime |
| Is 19991 a Pell Prime? | 19991 is NOT a Pell prime |
| Prime Factors | Prime factors of 19991 |
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19991 in other Numerals
| 19991 in Roman Numeral | XMXCMXCI |
| 19991 in Chinese Numeral | 壹萬玖仟玖佰玖拾壹 |
| 19991 in Egyptian Numeral | 𓂭𓇄𓍪𓎎𓏺 |
| 19991 in Babylonian Numeral |    |
Roots and stuff for 19991
| Is 19991 a square number? | 19991 is NOT a square number |
| Is 19991 a cube number? | 19991 is NOT a cube number |
| Square root of the number 19991 | 141.38953285162 |
| Cube root of the number 19991 | 27.140103928627 |
Recreational math for 19991
| Number 19991 reversed | 19991 |
| Sum of the digits | 29 |
| No of digits | 5 |