2781638 has 16 divisors (see below), whose sum is σ = 4458240. Its totient is φ = 1297800.

The previous prime is 2781637. The next prime is 2781677. The reversal of 2781638 is 8361872.

2781638 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 2781598 and 2781607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2781637) 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 7 ways as a sum of consecutive naturals, for example, 2183 + ... + 3213.

It is an arithmetic number, because the mean of its divisors is an integer number (278640).

2^2781638 is an apocalyptic number.

2781638 is a deficient number, since it is larger than the sum of its proper divisors (1676602).

2781638 is a wasteful number, since it uses less digits than its factorization.

2781638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1123.

The product of its digits is 16128, while the sum is 35.

The square root of 2781638 is about 1667.8243312771. The cubic root of 2781638 is about 140.6371974934.

The spelling of 2781638 in words is "two million, seven hundred eighty-one thousand, six hundred thirty-eight".