Mersenne primes – prime numbers of the order of 2n–1 – are considered significant in decoding encrypted data. Currently, there are 49 such numbers (the square of, again, a Mersenne prime). The most recently discovered number equals to 274,207,281–1, which also holds the record for the longest prime number, with nearly 24,000,000 digits! The Mersenne…
221B Baker Street happens to be the house of Sherlock Holmes. Incidentally, the number 221 has several significances. 221 = 13×17 is a product of two prime numbers. It is called a semi-prime number. Some other examples are 6(2×3), 10(2×5), 14(2×7), 21(3×7), 22(2×11), 26(2×13), 33(3×11), 35(5×7), 39(3×13), 49(7×7), 51(3×17), 55(5×11), 57(3×19), 62(2×31), 65(5×13), 69(3×23), 77(7×11),…
