2556640 has 72 divisors (see below), whose sum is σ = 6584760. Its totient is φ = 935424.

The previous prime is 2556607. The next prime is 2556641. The reversal of 2556640 is 466552.

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 2556599 and 2556608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2556641) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 88146 + ... + 88174.

It is an arithmetic number, because the mean of its divisors is an integer number (91455).

2^2556640 is an apocalyptic number.

2556640 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 2556640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3292380).

2556640 is an abundant number, since it is smaller than the sum of its proper divisors (4028120).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

2556640 is a wasteful number, since it uses less digits than its factorization.

2556640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92 (or 55 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 28.

The square root of 2556640 is about 1598.9496552425. The cubic root of 2556640 is about 136.7382003729.

It can be divided in two parts, 25 and 56640, that added together give a palindrome (56665).

The spelling of 2556640 in words is "two million, five hundred fifty-six thousand, six hundred forty".