Adding to 20081 its reverse (18002), we get a palindrome (38083).
It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18002 = 2 ⋅9001.
It is a cyclic number.
It is a Duffinian number.
It is a Curzon number.
It is a plaindrome in base 7.
It is a nialpdrome in base 12.
220081 is an apocalyptic number.
It is an amenable number.
20081 is an equidigital number, since it uses as much as digits as its factorization.
20081 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 510.
The square root of 20081 is about 141.7074451114. The cubic root of 20081 is about 27.1807714445.
The spelling of 20081 in words is "twenty thousand, eighty-one".