35

This number is a composite.

+ The number of pairs of twin primes less than 1000.

+ The first composite number occurring in Pascal's Triangle whose digit reversal is prime.

+ The product of 35 and 36 has the same prime factors as the product of 4374 and 4375. [Guy]

+ 35 is the smallest product of twin primes of the form (4*k+1, 4*k+3), k>0. [Zumkeller]

+ The number of known even numbers which are not the sum of two twin primes (coming from the same pair or not). [Capelle]

+ 35 can be written as a sum of odd primes in 35 ways, and as a sum of primes in 35 * 5 ways. [Hartley]

+ 35 = 23 + 33, i.e., the sum of the cubes of the first two primes. Factor 35 and get the third and fourth primes. [Mizuki]

+ 35 is the smallest number formed from two odd primes. It's prime factors are 5 and 7. Note that its digital sum (8) and digital product (15) are each one less than perfect squares. No prime number greater than 3 fits this category. [Storms]

+ The smallest number formed from twin primes and equal to the product of twin primes. [Silva]

+ A photograph printed in the popular 5 x 7 inch 'twin-prime' format has a semiprime area equal to 35 square inches. [Green]

(There are 7 curios for this number that have not yet been approved by an editor.)

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