19998 has 24 divisors (see below), whose sum is σ = 47736. Its totient is φ = 6000.

The previous prime is 19997. The next prime is 20011. The reversal of 19998 is 89991.

19998 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19991) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 148 + ... + 248.

It is an arithmetic number, because the mean of its divisors is an integer number (1989).

2¹⁹⁹⁹⁸ is an apocalyptic number.

19998 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 19998, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23868).

19998 is an abundant number, since it is smaller than the sum of its proper divisors (27738).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

19998 is a wasteful number, since it uses less digits than its factorization.

19998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120 (or 117 counting only the distinct ones).

The product of its digits is 5832, while the sum is 36.

The square root of 19998 is about 141.4142849927. The cubic root of 19998 is about 27.1432713299.

It can be divided in two parts, 1 and 9998, that added together give a palindrome (9999).

The spelling of 19998 in words is "nineteen thousand, nine hundred ninety-eight".