2556666 has 48 divisors (see below), whose sum is σ = 6424704. Its totient is φ = 719712.

The previous prime is 2556661. The next prime is 2556683. The reversal of 2556666 is 6666552.

2556666 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a d-powerful number, because it can be written as 2²¹ + 5⁷ + 5⁷ + 6⁵ + 6⁵ + 6⁵ + 6⁷ .

It is a plaindrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 2556666.

It is not an unprimeable number, because it can be changed into a prime (2556661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 12880 + ... + 13076.

It is an arithmetic number, because the mean of its divisors is an integer number (133848).

2^2556666 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2556666, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3212352).

2556666 is an abundant number, since it is smaller than the sum of its proper divisors (3868038).

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

2556666 is a wasteful number, since it uses less digits than its factorization.

2556666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 315 (or 312 counting only the distinct ones).

The product of its digits is 64800, while the sum is 36.

The square root of 2556666 is about 1598.9577855591. The cubic root of 2556666 is about 136.7386638955.

The spelling of 2556666 in words is "two million, five hundred fifty-six thousand, six hundred sixty-six".