27664 is a member of OEIS A138129: multiples of 1729, the Hardy-Ramanujan number, here 16 * 1729. The sequence begins:

0, 1729, 3458, 5187, 6916, 8645, 10374, 12103, 13832, 15561, 17290, 19019, 20748, 22477, 24206, 25935, 27664, 29393, 31122, 32851, 34580, 36309, 38038, 39767, ...

27664 is a practical, abundant, Zumkeller and pseudoperfect number.

27664 does not reach a home prime after 25 steps.

27664 has a digit sum of 25 and 27664 + 25 = 27689 which is a prime number

27664 can be rendered as a digit equation as follows:

-2 + 7 = 6 / 6 + 4