Adding to 20040 its reverse (4002), we get a palindrome (24042).
It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.
It is a plaindrome in base 7.
It is a nialpdrome in base 12.
It is a zygodrome in base 7.
20040 is an untouchable number, because it is not equal to the sum of proper divisors of any number.
220040 is an apocalyptic number.
20040 is a gapful number since it is divisible by the number (20) 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 20040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30240).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
20040 is a wasteful number, since it uses less digits than its factorization.
20040 is an evil number, because the sum of its binary digits is even.
The square root of 20040 is about 141.5627069535. The cubic root of 20040 is about 27.1622602327.
The spelling of 20040 in words is "twenty thousand, forty", and thus it is an iban number.