Names of 18
| Nominal | 18 |
| Cardinal | eighteen |
| Ordinal | 18th |
| This number as US currency | eighteen dollars |
| Is 18 an odd number? | 18 is NOT an odd number |
| Is 18 an even number? | 18 is an even number |
| Is 18 a palindrome? | 18 is NOT a palindrome number |
| Is 18 a triangle number? | 18 is NOT a triangle number |
18 in other Bases
| Base 2 (Binary) | 100102 |
| Base 3 (Ternary) | 2003 |
| Base 4 (Quaternary) | 1024 |
| Base 5 (Quinary) | 335 |
| Base 6 (Senary) | 306 |
| Base 8 (Octal) | 228 |
| Base 12 (Duodecimal) | 1612 |
| Base 16 (Hexadecimal) | 1216 |
| Base 20 (Vigesimal) | I20 |
Primes and Factors tests for 18
| Is 18 a Prime Number? | 18 is NOT a prime |
| Is 18 a perfect number? | 18 is NOT a perfect number |
| Is 18 a Mersenne Prime? | 18 is NOT a Mersenne prime |
| Is 18 a Fermat Prime? | 18 is NOT a Fermat prime |
| Is 18 a Fibonacci Prime? | 18 is NOT a Fibonacci prime |
| Is 18 a Partition Prime? | 18 is NOT a Partition prime |
| Is 18 a Pell Prime? | 18 is NOT a Pell prime |
| Prime Factors | Prime factors of 18 |
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18 in other Numerals
| 18 in Roman Numeral | XVIII |
| 18 in Chinese Numeral | 壹拾捌 |
| 18 in Egyptian Numeral | 𓎆𓐁 |
| 18 in Babylonian Numeral |  |
Roots and stuff for 18
| Is 18 a square number? | 18 is NOT a square number |
| Is 18 a cube number? | 18 is NOT a cube number |
| Square root of the number 18 | 4.2426406871193 |
| Cube root of the number 18 | 2.6207413942089 |
Recreational math for 18
| Number 18 reversed | 81 |
| Sum of the digits | 9 |
| No of digits | 2 |