60

From ProofWiki
Jump to navigation Jump to search

Previous  ... Next

Number

$60$ (sixty) is:

$2^2 \times 3 \times 5$


The $2$nd unitary perfect number after $6$:
$60 = 1 + 3 + 4 + 5 + 12 + 15 + 20$


The $4$th heptagonal pyramidal number after $1$, $8$, $26$:
$60 = 1 + 7 + 18 + 34 = \dfrac {4 \paren {4 + 1} \paren {5 \times 4 - 2} } 6$


The $5$th special highly composite number after $1$, $2$, $6$, $12$


The smallest positive integer which can be expressed as the sum of $2$ odd primes in $6$ ways:
$60 = 7 + 53 = 13 + 47 = 17 + 43 = 19 + 41 = 23 + 37 = 29 + 31$


The $9$th highly composite number after $1$, $2$, $4$, $6$, $12$, $24$, $36$, $48$:
$\map {\sigma_0} {60} = 12$


The $9$th superabundant number after $1$, $2$, $4$, $6$, $12$, $24$, $36$, $48$:
$\dfrac {\map {\sigma_1} {60} } {60} = \dfrac {168} {60} = 2 \cdotp 8$


The $11$th positive integer $n$ after $5$, $11$, $17$, $23$, $29$, $30$, $36$, $42$, $48$, $54$ such that no factorial of an integer can end with $n$ zeroes


The $14$th semiperfect number after $6$, $12$, $18$, $20$, $24$, $28$, $30$, $36$, $40$, $42$, $48$, $54$, $56$:
$60 = 10 + 20 + 30$


The $17$th highly abundant number after $1$, $2$, $3$, $4$, $6$, $8$, $10$, $12$, $16$, $18$, $20$, $24$, $30$, $36$, $42$, $48$:
$\map {\sigma_1} {60} = 168$


The $19$th of $21$ integers which can be represented as the sum of two primes in the maximum number of ways
$1$, $2$, $3$, $4$, $5$, $6$, $7$, $8$, $10$, $12$, $14$, $16$, $18$, $24$, $30$, $36$, $42$, $48$, $60$, $\ldots$


The $23$rd positive integer which is not the sum of $1$ or more distinct squares:
$2$, $3$, $6$, $7$, $8$, $11$, $12$, $15$, $18$, $19$, $22$, $23$, $24$, $27$, $28$, $31$, $32$, $33$, $43$, $44$, $47$, $48$, $60$, $\ldots$


The $35$th positive integer after $2$, $3$, $4$, $7$, $8$, $\ldots$, $44$, $45$, $46$, $49$, $50$, $54$, $55$, $59$ which cannot be expressed as the sum of distinct pentagonal numbers


The $37$th (strictly) positive integer after $1$, $2$, $3$, $\ldots$, $37$, $38$, $42$, $43$, $44$, $48$, $49$, $50$, $54$, $55$ which cannot be expressed as the sum of distinct primes of the form $6 n - 1$


The base of the sexagesimal system


The number of degrees in an internal angle of an equilateral triangle


Arithmetic Functions on $60$

\(\ds \map {\sigma_0} { 60 }\) \(=\) \(\ds 12\) $\sigma_0$ of $60$
\(\ds \map \phi { 60 }\) \(=\) \(\ds 16\) $\phi$ of $60$
\(\ds \map {\sigma_1} { 60 }\) \(=\) \(\ds 168\) $\sigma_1$ of $60$


Also see


Historical Note

There are $60$ seconds in a minute.

There are $60$ minutes of time in an hour, and $60$ minutes of angle in a degree.

These divisions date back to the time of the Babylonians, who used a $60$-based number system for their mathematics and astronomy.


Sources