What is your favorite Number? 1591521

While playing with the vowels of the English alphabet, I discovered the following facts about the mathematics of the vowels ---

The position occupied by the vowels in numbers are- a (1) e (5) i (9) o(15) and u (21). The numbers clearly show that all the vowel positions are odd numbers. It means there are no even vowels. The three vowel positions are divisible by 3. The two vowel positions are divisible by 5 and one vowel position is divisible by 7.

The other interesting play with the vowels is in terms of the scale. When all the vowel positions are written as a number, the number which is formed is 1591521. This is only divisible by 3 and none of the other 120549 available prime numbers less than 1591521.

$\frac{1591521}{3}=530507$, which is a prime number. It means the number formed is interesting to the number theorists.

When some manipulations are done on the digits of the number, this can give the scale, we are not sure up to which value but to a considerable large value. Here some manipulations mean we can arrange the digits of the number according to their order e.g. we can consider ($15$ or $91$ or $52$ ) or we can take ($59$ or $15$ or $21$) and so on but not the random ordering. we can construct a scale based on the digits available in $1591521$ as- $1=1$ (already there), $2=2$ (already there), $3=2+1$, $4=5-1$ or $2+1+1$, $5=5$ (already there),$ 6=5+1$;$7=5+2$; $8 =5+2+1$; $9= 5+5-1$; $10= 5+5$; $11=9+2$; $ 12=9+2+1 $ and so on.

By doing so, we can develop the scales continuously up to a large number using the available digits. Like some of the scales of large number are

 $43=59-15-1; 45=49-15+1; \\ 69=91-21-1; 70=91-21; \\  89=91-2; 100=91+5+2+1+1;\\120=21\times 5 +15;  200=21 \times 9 + 5+5+1 \\ $

and so on. This magical number seems interesting. Hence 1591521 is my best number for now.