199818 has 24 divisors (see below), whose sum is σ = 459108. Its totient is φ = 62592.

The previous prime is 199813. The next prime is 199819. The reversal of 199818 is 818991.

It can be written as a sum of positive squares in 2 ways, for example, as 199809 + 9 = 447^2 + 3^2 .

It is a nialpdrome in base 12.

It is not an unprimeable number, because it can be changed into a prime (199811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 21 + ... + 632.

2¹⁹⁹⁸¹⁸ is an apocalyptic number.

199818 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 199818, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (229554).

199818 is an abundant number, since it is smaller than the sum of its proper divisors (259290).

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

199818 is a wasteful number, since it uses less digits than its factorization.

199818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 678 (or 675 counting only the distinct ones).

The product of its digits is 5184, while the sum is 36.

The square root of 199818 is about 447.0100670007. The cubic root of 199818 is about 58.4626103397.

It can be divided in two parts, 1998 and 18, that added together give a triangular number (2016 = T₆₃).

The spelling of 199818 in words is "one hundred ninety-nine thousand, eight hundred eighteen".