It is a happy number.
It is a congruent number.
Almost surely, 266801798 is an apocalyptic number.
It is a practical number, because each smaller number is the sum of distinct divisors of 66801798, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (91231920).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
66801798 is a wasteful number, since it uses less digits than its factorization.
66801798 is an evil number, because the sum of its binary digits is even.
The square root of 66801798 is about 8173.2366905651. The cubic root of 66801798 is about 405.7539134950.
The spelling of 66801798 in words is "sixty-six million, eight hundred one thousand, seven hundred ninety-eight".