2556643 has 4 divisors (see below), whose sum is σ = 2560248. Its totient is φ = 2553040.

The previous prime is 2556641. The next prime is 2556661. The reversal of 2556643 is 3466552.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 2556643 - 2¹ = 2556641 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a d-powerful number, because it can be written as 2¹⁹ + 5⁷ + 5⁹ + 6² + 6² + 4⁵ + 3² .

It is a Duffinian number.

It is a plaindrome in base 15.

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 3 ways as a sum of consecutive naturals, for example, 346 + ... + 2287.

It is an arithmetic number, because the mean of its divisors is an integer number (640062).

2^2556643 is an apocalyptic number.

2556643 is a deficient number, since it is larger than the sum of its proper divisors (3605).

2556643 is an equidigital number, since it uses as much as digits as its factorization.

2556643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3604.

The product of its digits is 21600, while the sum is 31.

The square root of 2556643 is about 1598.9505933580. The cubic root of 2556643 is about 136.7382538564.

Subtracting 2556643 from its reverse (3466552), we obtain a palindrome (909909).

The spelling of 2556643 in words is "two million, five hundred fifty-six thousand, six hundred forty-three".