It is a happy number.
169581 is digitally balanced in base 7, because in such base it contains all the possibile digits an equal number of times.
It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 185961 = 3 ⋅61987.
It is a D-number.
It is a Duffinian number.
169581 is strictly pandigital in base 7.
It is a congruent number.
It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 169581.
2169581 is an apocalyptic number.
It is an amenable number.
169581 is an equidigital number, since it uses as much as digits as its factorization.
169581 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 56530.
The square root of 169581 is about 411.8021369541. The cubic root of 169581 is about 55.3510330306.
The spelling of 169581 in words is "one hundred sixty-nine thousand, five hundred eighty-one".