1809

1809 = 3 x 3 x 3 x 67.

1809 is the sum of the first 26 palindromes (A046489).

1809 is the sum of the first 17 primes whose indices are primes (A083186).

1809 is a non-palindromic balanced number; the first and last half of its digits have the same sum (A145808).

1809 is a multiple of 9 that contains 9 in its decimal representation (A121029).

1809 is 3421 in base 8. It is 809 in base 15.

1809 divides 37³ - 1.

Source: OEIS