Names of 1661
| Nominal | 1661 |
| Cardinal | one thousand six hundred sixty-one |
| Ordinal | 1,661st |
| This number as US currency | one thousand six hundred sixty-one dollars |
| Is 1661 an odd number? | 1661 is an odd number |
| Is 1661 an even number? | 1661 is NOT an even number |
| Is 1661 a palindrome? | 1661 is a palindrome number |
| Is 1661 a triangle number? | 1661 is NOT a triangle number |
1661 in other Bases
| Base 2 (Binary) | 110011111012 |
| Base 3 (Ternary) | 20211123 |
| Base 4 (Quaternary) | 1213314 |
| Base 5 (Quinary) | 231215 |
| Base 6 (Senary) | 114056 |
| Base 8 (Octal) | 31758 |
| Base 12 (Duodecimal) | B6512 |
| Base 16 (Hexadecimal) | 67D16 |
| Base 20 (Vigesimal) | 43120 |
Primes and Factors tests for 1661
| Is 1661 a Prime Number? | 1661 is NOT a prime |
| Is 1661 a perfect number? | 1661 is NOT a perfect number |
| Is 1661 a Mersenne Prime? | 1661 is NOT a Mersenne prime |
| Is 1661 a Fermat Prime? | 1661 is NOT a Fermat prime |
| Is 1661 a Fibonacci Prime? | 1661 is NOT a Fibonacci prime |
| Is 1661 a Partition Prime? | 1661 is NOT a Partition prime |
| Is 1661 a Pell Prime? | 1661 is NOT a Pell prime |
| Prime Factors | Prime factors of 1661 |
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1661 in other Numerals
| 1661 in Roman Numeral | MDCLXI |
| 1661 in Chinese Numeral | 壹仟陸佰陸拾壹 |
| 1661 in Egyptian Numeral | 𓆼𓍧𓎋𓏺 |
| 1661 in Babylonian Numeral |   |
Roots and stuff for 1661
| Is 1661 a square number? | 1661 is NOT a square number |
| Is 1661 a cube number? | 1661 is NOT a cube number |
| Square root of the number 1661 | 40.75536774463 |
| Cube root of the number 1661 | 11.84285860488 |
Recreational math for 1661
| Number 1661 reversed | 1661 |
| Sum of the digits | 14 |
| No of digits | 4 |