209988 has 36 divisors (see below), whose sum is σ = 560560. Its totient is φ = 66096.

The previous prime is 209987. The next prime is 210011. The reversal of 209988 is 889902.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a plaindrome in base 16.

It is a zygodrome in base 16.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 209988.

It is not an unprimeable number, because it can be changed into a prime (209983) 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, 531 + ... + 837.

2²⁰⁹⁹⁸⁸ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 209988, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (280280).

209988 is an abundant number, since it is smaller than the sum of its proper divisors (350572).

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

209988 is a wasteful number, since it uses less digits than its factorization.

209988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 336 (or 331 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 36.

The square root of 209988 is about 458.2444762351. The cubic root of 209988 is about 59.4380873305.

It can be divided in two parts, 2099 and 88, that added together give a 7-th power (2187 = 3⁷).

The spelling of 209988 in words is "two hundred nine thousand, nine hundred eighty-eight".