171

From Wikipedia:

171 is an odd natural number between 170 and 172.

171 is a Harshad number, divisible by the sum of its digits.

171 is a palindromic number and an undulating number.

171 is a triangular number and a 13-gonal and 58-gonal number.

171 is a repdigit in base 7.

And from the FDIC:

171 is the number of banks which are currently on the FDIC list of unstable banks....

And an unreliable source says Citibank was not on that list...