27685 is a product of a 4k+3 prime raised to an even power and two 4k+1 primes. Thus it can be expressed as a sum of two squares in two ways viz. 42 ^2 + 161^2 and 63^2 + 154^2.

27685 is a number with no repeating digits whose arithmetic digital root (1) and its multiplicative digital root (0) are different from any of the digits of the number. The previous number (27684) also has this property. See Bespoken for Sequences entry.

27685 is a Duffinian number.

27685 can be rendered as a digit equation as follows:

2 + 7 - 6 = 8 - 5