It is a weak prime.
It is a cyclic number.
Almost surely, 2121220111221553 is an apocalyptic number.
It is an amenable number.
121220111221553 is an equidigital number, since it uses as much as digits as its factorization.
121220111221553 is an odious number, because the sum of its binary digits is odd.
Adding to 121220111221553 its reverse (355122111022121), we get a palindrome (476342222243674).
The spelling of 121220111221553 in words is "one hundred twenty-one trillion, two hundred twenty billion, one hundred eleven million, two hundred twenty-one thousand, five hundred fifty-three".