27709 is a product of a 4k+3 prime (11) raised to an even power (2) and a 4k+1 prime (229). Thus it can be expressed as a sum of two squares in one way only viz. 22^2 + 165^2.

27709 is number with an odd number of digits (>=3) whose SOD to left and right of middle digit are the same & with middle digit is equal to the arithmetic digital root of number, here 7. See Bespoken for Sequences entry.

The numbers from 27709 up to 40000 are:

27709, 27718, 27727, 27736, 27745, 27754, 27763, 27772, 27781, 27790, 27809, 27818, 27827, 27836, 27845, 27854, 27863, 27872, 27881, 27890, 27909, 27918, 27927, 27936, 27945, 27954, 27963, 27972, 27981, 27990, 36109, 36118, 36127, 36136, 36145, 36154, 36163, 36172, 36181, 36190, 36209, 36218, 36227, 36236, 36245, 36254, 36263, 36272, 36281, 36290, 36309, 36318, 36327, 36336, 36345, 36354, 36363, 36372, 36381, 36390, 36409, 36418, 36427, 36436, 36445, 36454, 36463, 36472, 36481, 36490, 36509, 36518, 36527, 36536, 36545, 36554, 36563, 36572, 36581, 36590, 36609, 36618, 36627, 36636, 36645, 36654, 36663, 36672, 36681, 36690, 36709, 36718, 36727, 36736, 36745, 36754, 36763, 36772, 36781, 36790, 36809, 36818, 36827, 36836, 36845, 36854, 36863, 36872, 36881, 36890, 36909, 36918, 36927, 36936, 36945, 36954, 36963, 36972, 36981, 36990

27709 is a Duffinian number.

27709 is the second member of an interesting number chain (which is base independent):

27708 = 12 × 2309

27709 = 11 × 2519

27710 = 10 × 2771

27711 = 9 × 3079

27712 = 8 × 3464

27713 = 7 x 3959

27714 = 6 × 4619

27715 = 5 x 5543

27716 = 4 × 6929

27717 = 3 × 9239

27718 = 2 × 13859

27709 has a sum of cubes of digits that is a prime number viz. 1423.

27709 can be rendered as a digit equation as follows:

2 + 7 = 7 * 0 + 9