It is an Ulam number.
It is a plaindrome in base 11.
It is a zygodrome in base 7.
It is a congruent number.
It is an unprimeable number.
21999984 is an apocalyptic number.
1999984 is a gapful number since it is divisible by the number (14) formed by its first and last digit.
It is an amenable number.
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
1999984 is a wasteful number, since it uses less digits than its factorization.
1999984 is an odious number, because the sum of its binary digits is odd.
The square root of 1999984 is about 1414.2079055075. The cubic root of 1999984 is about 125.9917690096.
The spelling of 1999984 in words is "one million, nine hundred ninety-nine thousand, nine hundred eighty-four".