Adding to 21140 its reverse (4112), we get a palindrome (25252).
It is a congruent number.
221140 is an apocalyptic number.
21140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.
It is an amenable number.
It is a practical number, because each smaller number is the sum of distinct divisors of 21140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25536).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
21140 is a wasteful number, since it uses less digits than its factorization.
21140 is an evil number, because the sum of its binary digits is even.
The square root of 21140 is about 145.3960109494. The cubic root of 21140 is about 27.6504154492.
The spelling of 21140 in words is "twenty-one thousand, one hundred forty", and thus it is an iban number.