It is a happy number.
It is a Curzon number.
It is a self number, because there is not a number n which added to its sum of digits gives 81758.
It is a congruent number.
It is an unprimeable number.
81758 is an untouchable number, because it is not equal to the sum of proper divisors of any number.
281758 is an apocalyptic number.
81758 is a wasteful number, since it uses less digits than its factorization.
81758 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 40881.
The square root of 81758 is about 285.9335587160. The cubic root of 81758 is about 43.4020343501.
The spelling of 81758 in words is "eighty-one thousand, seven hundred fifty-eight".