It is a congruent number.
It is an unprimeable number.
Almost surely, 21605217116 is an apocalyptic number.
It is an amenable number.
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
1605217116 is a wasteful number, since it uses less digits than its factorization.
1605217116 is an evil number, because the sum of its binary digits is even.
The square root of 1605217116 is about 40065.1608757534. The cubic root of 1605217116 is about 1170.8769610448.
The spelling of 1605217116 in words is "one billion, six hundred five million, two hundred seventeen thousand, one hundred sixteen".