It is a semiprime because it is the product of two primes.
It is an Ulam number.
It is an alternating number because its digits alternate between even and odd.
It is a Curzon number.
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 21254.
It is an unprimeable number.
221254 is an apocalyptic number.
21254 is a wasteful number, since it uses less digits than its factorization.
21254 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 10629.
The square root of 21254 is about 145.7875166124. The cubic root of 21254 is about 27.7000291067.
Adding to 21254 its reverse (45212), we get a palindrome (66466).
The spelling of 21254 in words is "twenty-one thousand, two hundred fifty-four".