It is a nialpdrome in base 16.
It is a zygodrome in base 2 and base 16.
2209664 is an apocalyptic number.
209664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.
It is an amenable number.
It is a practical number, because each smaller number is the sum of distinct divisors of 209664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (372008).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
209664 is a wasteful number, since it uses less digits than its factorization.
209664 is an evil number, because the sum of its binary digits is even.
The square root of 209664 is about 457.8908166801. The cubic root of 209664 is about 59.4075016883.
The spelling of 209664 in words is "two hundred nine thousand, six hundred sixty-four".