It is a plaindrome in base 15.
It is a nialpdrome in base 12.
It is a congruent number.
21240 is an apocalyptic number.
1240 is a gapful number since it is divisible by the number (10) 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 1240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1440).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
1240 is a wasteful number, since it uses less digits than its factorization.
1240 is an odious number, because the sum of its binary digits is odd.
The square root of 1240 is about 35.2136337233. The cubic root of 1240 is about 10.7433707099.
Adding to 1240 its reverse (421), we get a palindrome (1661).
The spelling of 1240 in words is "one thousand, two hundred forty", and thus it is an iban number.