1900

1900 = 2² x 5² x 19.

1900 has the representation 1900 = 2³ 3⁵ - 44.

There are 1900 prime numbers less than or equal to 2¹⁵.

1900 is a 13-gonal (triskaeidecagonal or tridecagonal) number.

1900 is the sum of eight consecutive primes: 1900 = 223 + 227 + 229 + 233 + 239 + 241 + 251 + 257.

1900 is the largest palindrome in Roman numerals: MCM.

Source: On-Line Encyclopedia of Integer Sequences