1998 is nontrivially palindromic in base 14.
1998 is an esthetic number in base 13, because in such base its adjacent digits differ by 1.
1998 is an undulating number in base 14.
It is a plaindrome in base 11 and base 16.
It is a nialpdrome in base 7 and base 13.
It is a congruent number.
1998 is a gapful number since it is divisible by the number (18) formed by its first and last digit.
It is a practical number, because each smaller number is the sum of distinct divisors of 1998, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2280).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
1998 is a wasteful number, since it uses less digits than its factorization.
1998 is an evil number, because the sum of its binary digits is even.
The square root of 1998 is about 44.6989932773. The cubic root of 1998 is about 12.5950093614.
Adding to 1998 its sum of digits (27), we get a square (2025 = 452).
The spelling of 1998 in words is "one thousand, nine hundred ninety-eight".