198990 has 64 divisors (see below), whose sum is σ = 587520. Its totient is φ = 47520.

The previous prime is 198977. The next prime is 198997. The reversal of 198990 is 99891.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (198997) by changing a digit.

198990 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2937 + ... + 3003.

It is an arithmetic number, because the mean of its divisors is an integer number (9180).

2¹⁹⁸⁹⁹⁰ is an apocalyptic number.

198990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 198990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (293760).

198990 is an abundant number, since it is smaller than the sum of its proper divisors (388530).

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

198990 is a wasteful number, since it uses less digits than its factorization.

198990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94 (or 88 counting only the distinct ones).

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

The square root of 198990 is about 446.0829519271. The cubic root of 198990 is about 58.3817466567.

Subtracting from 198990 its reverse (99891), we obtain a palindrome (99099).

It can be divided in two parts, 19 and 8990, that added together give a palindrome (9009).

The spelling of 198990 in words is "one hundred ninety-eight thousand, nine hundred ninety".