It is a semiprime because it is the product of two primes.
It is a cyclic number.
It is a nialpdrome in base 15.
It is a self number, because there is not a number n which added to its sum of digits gives 21695.
It is a congruent number.
It is an unprimeable number.
221695 is an apocalyptic number.
21695 is an equidigital number, since it uses as much as digits as its factorization.
21695 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 4344.
The square root of 21695 is about 147.2922265430. The cubic root of 21695 is about 27.8903020811.
The spelling of 21695 in words is "twenty-one thousand, six hundred ninety-five".