It is a weak prime.
It is a cyclic number.
It is a de Polignac number, because none of the positive numbers 2k-21213543315073 is a prime.
Almost surely, 221213543315073 is an apocalyptic number.
It is an amenable number.
21213543315073 is an equidigital number, since it uses as much as digits as its factorization.
21213543315073 is an evil number, because the sum of its binary digits is even.
Adding to 21213543315073 its reverse (37051334531212), we get a palindrome (58264877846285).
The spelling of 21213543315073 in words is "twenty-one trillion, two hundred thirteen billion, five hundred forty-three million, three hundred fifteen thousand, seventy-three".