2556 has 18 divisors (see below), whose sum is σ = 6552.
Its totient is φ = 840.
The previous prime is 2551. The next prime is 2557. The reversal of 2556 is 6552.
It can be divided in two parts, 25 and 56, that added together give a 4-th power (81 = 34).
2556 is nontrivially palindromic in base 8.
2556 is a nontrivial binomial coefficient, being equal to C(72, 2).
It is a tau number, because it is divible by the number of its divisors (18).
It is a Smith number, since the sum of its digits (18) coincides with the sum of the digits of its prime factors.
It is a Harshad number since it is a multiple of its sum of digits (18).
It is a plaindrome in base 10.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (2551) by changing a digit.
It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1 + ... + 71.
It is an arithmetic number, because the mean of its divisors is an integer number (364).
2556 is the 71-st triangular number and also the 36-th hexagonal number.
It is an amenable number.
It is a practical number, because each smaller number is the sum of distinct divisors of 2556, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3276).
2556 is an abundant number, since it is smaller than the sum of its proper divisors (3996).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
2556 is a wasteful number, since it uses less digits than its factorization.
2556 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 81 (or 76 counting only the distinct ones).
The product of its digits is 300, while the sum is 18.
The square root of 2556 is about 50.5568986391.
The cubic root of 2556 is about 13.6726789595.
The spelling of 2556 in words is "two thousand, five hundred fifty-six".