Subtracting from 2640 its sum of digits (12), we obtain a triangular number (2628 = T72).
2640 divided by its product of nonzero digits (48) gives a palindrome (55).
2640 is nontrivially palindromic in base 9.
2640 is an esthetic number in base 3, because in such base its adjacent digits differ by 1.
It is a tau number, because it is divible by the number of its divisors (40).
It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.
It is a nialpdrome in base 4, base 15 and base 16.
It is a zygodrome in base 4.
It is a congruent number.
2640 is an untouchable number, because it is not equal to the sum of proper divisors of any number.
2640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.
2640 is the 30-th octagonal number.
It is an amenable number.
It is a practical number, because each smaller number is the sum of distinct divisors of 2640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4464).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
2640 is a wasteful number, since it uses less digits than its factorization.
2640 is an evil number, because the sum of its binary digits is even.
The square root of 2640 is about 51.3809303147. The cubic root of 2640 is about 13.8208464600.
The spelling of 2640 in words is "two thousand, six hundred forty".