Adding to 40020 its reverse (2004), we get a palindrome (42024).
40020 is nontrivially palindromic in base 9 and base 11.
It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.
It is a congruent number.
It is an unprimeable number.
40020 is an untouchable number, because it is not equal to the sum of proper divisors of any number.
240020 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 40020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (60480).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
40020 is a wasteful number, since it uses less digits than its factorization.
40020 is an odious number, because the sum of its binary digits is odd.
The square root of 40020 is about 200.0499937516. The cubic root of 40020 is about 34.2052179036.
The spelling of 40020 in words is "forty thousand, twenty", and thus it is an iban number.