- In
number theory, a
deficient number or
defective number is a
positive integer n for
which the sum of
divisors of n is less than 2n. Equivalently, it...
-
nontotient number (including odd
numbers > 1) the 36th
arithmetic number, the 38th
composite number (where the
abundance of 55 = - 38), the 43rd
deficient number...
-
sphenic number, an
extravagant number, a
lucky number, a
polite number, an
amenable number, and a
deficient number. 777 is a
congruent number, as it is...
-
higher prime. a
deficient number, a
lucky number, a bell
number (i.e., the
number of
partitions for a set of size 4), a
pentatope number, and a repdigit...
-
distinct previously occurring Ulam
numbers in a sequence. 69 is a
deficient number because the sum of its
proper divisors (which
excludes itself) is less...
- the
natural number following 168 and
preceding 170. 169 is an odd
number, a
composite number, and a
deficient number. 169 is a
square number: 13 × 13 =...
- 1291. It is
classified as an
apocalyptic power, a
deficient number, and an evil
number: The
number 1289 is
called an
apocalyptic power because 21289 contains...
- fifty-five) is the
natural number following 154 and
preceding 156. 155 is: a
composite number a semiprime. a
deficient number,
since 1+5+31=37<155. odious...
-
primitive abundant number is an
abundant number whose proper divisors are all
deficient numbers. For example, 20 is a
primitive abundant number because: The...
- 90, 102, 104, ... (sequence A181487 in the OEIS)
Every deficient number and
every perfect number is in S {\displaystyle {\mathcal {S}}}
because the restriction...
