It is a happy number.
12101 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.
It is a weak prime.
It is a cyclic number.
It is a Sophie Germain prime.
It is an alternating number because its digits alternate between odd and even.
It is a Curzon number.
It is a plaindrome in base 13 and base 15.
It is a congruent number.
12101 is a Friedman number, since it can be written as 110^2+1, using all its digits and the basic arithmetic operations.
212101 is an apocalyptic number.
It is an amenable number.
12101 is an equidigital number, since it uses as much as digits as its factorization.
12101 is an evil number, because the sum of its binary digits is even.
The square root of 12101 is about 110.0045453606. The cubic root of 12101 is about 22.9583366729.
Adding to 12101 its reverse (10121), we get a palindrome (22222).
Multiplying 12101 by its reverse (10121), we get a palindrome (122474221).
The spelling of 12101 in words is "twelve thousand, one hundred one", and thus it is an iban number.