List of Numbers
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Properties of the Number 21
- Because 21 is not divisible by 2 ...
- 21 is an odd number
- 21 has parity 1
- 21 is not an even number
- Because 21 can be factored as 3 x 7 ...
- 21 is a composite number
- 21 is not a prime number
Alternative Representations of the Number 21
- Base 2 (binary): 10101
- Base 8 (octal): 25
- Base 16 (hexadecimal): 15
Divisors of the Number 21
- 21 has 4 positive divisors:
1, 3, 7, 21
- The sum of the positive divisors is 32
- 21 has 3 proper divisors:
1, 3, 7
- The sum of the proper divisors is 11
- 21 is a deficient number since the sum of the proper divisors is less than 21
- 21 is not a perfect number
- 21 is not an abundant number
More Properties of the Number 21
- 21 is not a square number
- 21 is not a cube number
- 21 is not a palindromic number
- 21 is a Fibonacci number
- 21 is not a Lucas number
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