All odd numbers with one or two distinct prime factors are deficient. Since 3 and 7 are factors of 63, it must be deficient.
17 is a deficient number because half the sum its factors is less than 17 [(1 + 17)/2 = 9)]. All odd numbers less than 945 are deficient.
All prime numbers are deficient.
Yes, the factors of all odd numbers are odd numbers.
No. From Wikipedia: "The first few deficient numbers are: 1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 19, 21, 22, 23, 25, 26, 27, ..." As you can see, the list includes both even and odd numbers. For example, all powers of two are deficient.
With exception of the number 2, all prime numbers are odd. However, not all odd numbers are prime.
All prime numbers are odd with the only exception of the prime number 2. However, not all odd numbers are prime.
All of the odd numbers.
There are more deficient numbers.
Half of all square numbers are odd. They are the ones which are the square of an odd number.
With the exception of 2, all primes are odd numbers, therefore the answer is no.