263 Mathematically

                                                           263

1. 263 is a Ramanujan prime.

Ramanujan prime is a prime number that satisfies a result proven by Srinivasa Ramanujan relating to the prime-counting function.

( https://en.wikipedia.org/wiki/Ramanujan_prime )

2. 263^2=69169 is a strobogrammatic number that appears the same rotated by 180 degree.

3. 263 = 43 + 47 + 53 + 59 + 61

(Sum of 5 Prime numbers).

4.It is a happy number. Read about Happy number in the following link.

https://www.myqbook.com/MathConcept/667/Happy-numbers

5.It is a balanced prime.

263 = 257+ 269

2

https://en.wikipedia.org/wiki/Balanced_prime

6. It is a Chen Prime.

https://en.wikipedia.org/wiki/Chen_prime

Thanks for reading

Dr Rajesh Kumar Thakur

Mathematically 260

                                                                  260

1. It is a composite number.
2. It is the product of 3 three prime numbers-2, 3 and 13                                                                             260 = 2 x 2 x 5 x 13
3. It is the number of days in Mayan Calender
4. It is the magic sum of a 8 by 8 magic square. 
   
5. It is also the sum of Franklin magic square 
   

Dr. Rajesh Kumar Thakur

Source :- 

1. Wikipedia

2. Pats' Blog

3. The Power of Mathematical number