2640 has 40 divisors (see below), whose sum is σ = 8928. Its totient is φ = 640.

The previous prime is 2633. The next prime is 2647. The reversal of 2640 is 462.

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 an interprime number because it is at equal distance from previous prime (2633) and next prime (2647).

It is a tau number, because it is divible by the number of its divisors (40).

It is a hoax number, since the sum of its digits (12) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (12).

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.

It is not an unprimeable number, because it can be changed into a prime (2647) by changing a digit.

2640 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 235 + ... + 245.

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).

2640 is an abundant number, since it is smaller than the sum of its proper divisors (6288).

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 sum of its prime factors is 27 (or 21 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 12.

The square root of 2640 is about 51.3809303147. The cubic root of 2640 is about 13.8208464600.

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).

It can be divided in two parts, 26 and 40, that added together give a palindrome (66).

The spelling of 2640 in words is "two thousand, six hundred forty".