36
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Number
$36$ (thirty-six) is:
- $2^2 \times 3^2$
- The $2$nd power of $6$ after $(1)$, $6$:
- $36 = 6^2$
- The $2$nd number after $1$ to be both square and triangular:
- $36 = 6^2 = \dfrac {8 \times \paren {8 + 1} } 2$
- The $3$rd square number after $1$, $4$ to be the divisor sum value of some (strictly) positive integer:
- $36 = \map {\sigma_1} {22}$
- The $3$rd of three $2$-digit integers divisible by both the sum and product of its digits:
- $36 = \paren {3 + 6} \times 4 = \paren {3 \times 6} \times 2$
- The $6$th square number after $1$, $4$, $9$, $16$, $25$:
- $36 = 6 \times 6$
- The $6$th square after $1$, $4$, $9$, $16$, $25$ which has no more than $2$ distinct digits and does not end in $0$:
- $36 = 6^2$
- The $6$th abundant number after $12$, $18$, $20$, $24$, $30$:
- $1 + 2 + 3 + 4 + 6 + 9 + 12 + 18 = 55 > 36$
- The $7$th positive integer $n$ after $5$, $11$, $17$, $23$, $29$, $30$ such that no factorial of an integer can end with $n$ zeroes.
- The $7$th superabundant number after $1$, $2$, $4$, $6$, $12$, $24$:
- $\dfrac {\map {\sigma_1} {36} } {36} = \dfrac {91} {36} = 2 \cdotp 52 \dot 7$
- The $7$th highly composite number after $1$, $2$, $4$, $6$, $12$, $24$:
- $\map {\sigma_0} {36} = 9$
- The $8$th triangular number after $1$, $3$, $6$, $10$, $15$, $21$, $28$:
- $36 = 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 = \dfrac {8 \times \paren {8 + 1} } 2$
- The $8$th semiperfect number after $6$, $12$, $18$, $20$, $24$, $28$, $30$:
- $36 = 3 + 6 + 9 + 18$
- The $9$th powerful number after $1$, $4$, $8$, $9$, $16$, $25$, $27$, $32$
- The $13$th Ulam number after $1$, $2$, $3$, $4$, $6$, $8$, $11$, $13$, $16$, $18$, $26$, $28$:
- $36 = 8 + 28$
- The $14$th highly abundant number after $1$, $2$, $3$, $4$, $6$, $8$, $10$, $12$, $16$, $18$, $20$, $24$, $30$:
- $\map {\sigma_1} {36} = 91$
- The $14$th Zuckerman number after $1$, $2$, $3$, $4$, $5$, $6$, $7$, $8$, $9$, $11$, $12$, $15$, $24$:
- $36 = 2 \times 18 = 2 \times \left({3 \times 6}\right)$
- The $14$th of $35$ integers less than $91$ to which $91$ itself is a Fermat pseudoprime:
- $3$, $4$, $9$, $10$, $12$, $16$, $17$, $22$, $23$, $25$, $27$, $29$, $30$, $36$, $\ldots$
- The $16$th after $1$, $2$, $3$, $4$, $5$, $6$, $7$, $8$, $10$, $12$, $14$, $16$, $18$, $24$, $30$ of $21$ integers which can be represented as the sum of two primes in the maximum number of ways
- The $18$th harshad number after $1$, $2$, $3$, $4$, $5$, $6$, $7$, $8$, $9$, $10$, $12$, $18$, $20$, $21$, $24$, $27$, $30$:
- $36 = 4 \times 9 = 4 \times \paren {3 + 6}$
- The $20$th after $1$, $2$, $4$, $5$, $6$, $8$, $9$, $12$, $13$, $15$, $16$, $17$, $20$, $24$, $25$, $27$, $28$, $32$, $35$ of the $24$ positive integers which cannot be expressed as the sum of distinct non-pythagorean primes.
- The $26$th (strictly) positive integer after $1$, $2$, $3$, $\ldots$, $20$, $21$, $24$, $25$, $26$, $27$, $30$, $31$, $32$, $35$ which cannot be expressed as the sum of distinct primes of the form $6 n - 1$
- The $26$th integer $n$ such that $2^n$ contains no zero in its decimal representation:
- $2^{36} = 68 \, 719 \, 476 \, 736$
- The total of all the entries in a magic cube of order $2$ (if it were to exist), after $1$:
- $36 = \ds \sum_{k \mathop = 1}^{2^3} k = \dfrac {2^3 \paren {2^3 + 1} } 2$
- $35$ and $4374$ have the same prime factors between them as $36$ and $4375$:
- $35 = 5 \times 7$, $4374 = 2 \times 3^7$; $36 = 2^2 \times 3^2$, $4375 = 5^4 \times 7$
Also see
- Previous ... Next: Highly Composite Number
- Previous ... Next: Superabundant Number
- Previous ... Next: Zuckerman Number
- Previous: 2-Digit Numbers divisible by both Product and Sum of Digits
- Previous ... Next: Ulam Number
- Previous ... Next: Triangular Number
- Previous ... Next: 91 is Pseudoprime to 35 Bases less than 91
- Previous ... Next: Abundant Number
- Previous ... Next: Semiperfect Number
- Previous ... Next: Harshad Number
- Previous ... Next: Highly Abundant Number
- Previous ... Next: Numbers of Zeroes that Factorial does not end with
- Previous ... Next: Integers whose Number of Representations as Sum of Two Primes is Maximum
- Previous ... Next: Powerful Number
- Previous ... Next: Integers not Expressible as Sum of Distinct Primes of form 6n-1
- Previous ... Next: Powers of 2 with no Zero in Decimal Representation
- Previous ... Next: Positive Integers Not Expressible as Sum of Distinct Non-Pythagorean Primes
Historical Note
The number $36$ was held in particularly high regard by the ancient Greeks, as it is the sum of the first $4$ even numbers and the first $4$ odd numbers.
Sources
- 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $36$
- 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $36$
Categories:
- Powers of 6/Examples
- Highly Composite Numbers/Examples
- Superabundant Numbers/Examples
- Zuckerman Numbers/Examples
- Square Numbers/Examples
- Ulam Numbers/Examples
- Triangular Numbers/Examples
- Abundant Numbers/Examples
- Semiperfect Numbers/Examples
- Harshad Numbers/Examples
- Highly Abundant Numbers/Examples
- Powerful Numbers/Examples
- Integers not Expressible as Sum of Distinct Primes of form 6n-1/Examples
- Specific Numbers
- 36