665

665 = 5 x 7 x 19.

665 is the only odd multiple of 5 that is expressible as the difference of sixth powers of two consecutive (2 and 3) primes: 3⁶ – 2⁶ = 665.

665 is 555 in base 11.

665 is a divisor of 11³ - 1.


The Indian mathematician and astronomer Brahmagupta (born 598) died in the year 665.

Source: Prime Curios!