Names of 21990
| Nominal | 21990 |
| Cardinal | twenty-one thousand nine hundred ninety |
| Ordinal | 21,990th |
| This number as US currency | twenty-one thousand nine hundred ninety dollars |
| Is 21990 an odd number? | 21990 is NOT an odd number |
| Is 21990 an even number? | 21990 is an even number |
| Is 21990 a palindrome? | 21990 is NOT a palindrome number |
| Is 21990 a triangle number? | 21990 is NOT a triangle number |
21990 in other Bases
| Base 2 (Binary) | 1010101111001102 |
| Base 3 (Ternary) | 10100111103 |
| Base 4 (Quaternary) | 111132124 |
| Base 5 (Quinary) | 12004305 |
| Base 6 (Senary) | 2454506 |
| Base 8 (Octal) | 527468 |
| Base 12 (Duodecimal) | 1088612 |
| Base 16 (Hexadecimal) | 55E616 |
| Base 20 (Vigesimal) | 2EJA20 |
Primes and Factors tests for 21990
| Is 21990 a Prime Number? | 21990 is NOT a prime |
| Is 21990 a perfect number? | 21990 is NOT a perfect number |
| Is 21990 a Mersenne Prime? | 21990 is NOT a Mersenne prime |
| Is 21990 a Fermat Prime? | 21990 is NOT a Fermat prime |
| Is 21990 a Fibonacci Prime? | 21990 is NOT a Fibonacci prime |
| Is 21990 a Partition Prime? | 21990 is NOT a Partition prime |
| Is 21990 a Pell Prime? | 21990 is NOT a Pell prime |
| Prime Factors | Prime factors of 21990 |
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21990 in other Numerals
| 21990 in Roman Numeral | XXMCMXC |
| 21990 in Chinese Numeral | 貳萬壹仟玖佰玖拾 |
| 21990 in Egyptian Numeral | 𓂮𓆼𓍪𓎎 |
| 21990 in Babylonian Numeral |   |
Roots and stuff for 21990
| Is 21990 a square number? | 21990 is NOT a square number |
| Is 21990 a cube number? | 21990 is NOT a cube number |
| Square root of the number 21990 | 148.29025591724 |
| Cube root of the number 21990 | 28.016147148994 |
Recreational math for 21990
| Number 21990 reversed | 09912 |
| Sum of the digits | 21 |
| No of digits | 5 |