27730 is a number n such that n plus digit sum of n and (n+1) plus digit sum of (n+1) are both prime. Here :

27730 + 19 = 27749 (prime)

27731 +2 1 = 27751 (prime)

27730 is equal to the binomial coefficient C(236, 2).

27730 is the third number in a run of FOUR consecutive positive negabinary-Niven numbers. The first number is 27728.

27730 is a junction number because it is equal to n + sod(n) for n = 27698 and 27707.

27730 has a sum of distinct prime factors (113) that is a prime number.

27730 has a sum of digits (19) that is prime.

27730 is the 235-th triangular number.

27730 is 118-th hexagonal number.

27730 is the 79-th centered nonagonal number.

27730 is a nialpdrome in base 13 : c811.

27730 is a xenodrome in base 9 : 42031.

27730 can be rendered as a digit equation as follows:

2 + 7 / 7 = 3 + 0