6855781 has 4 divisors (see below), whose sum is σ = 6871500. Its totient is φ = 6840064.

The previous prime is 6855769. The next prime is 6855787. The reversal of 6855781 is 1875586.

6855781 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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

It can be written as a sum of positive squares in 2 ways, for example, as 3648100 + 3207681 = 1910^2 + 1791^2 .

It is a cyclic number.

It is not a de Polignac number, because 6855781 - 2¹¹ = 6853733 is a prime.

It is a super-2 number, since 2×6855781² = 94003466239922, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6855787) 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 3 ways as a sum of consecutive naturals, for example, 7186 + ... + 8083.

It is an arithmetic number, because the mean of its divisors is an integer number (1717875).

Almost surely, 2^6855781 is an apocalyptic number.

It is an amenable number.

6855781 is a deficient number, since it is larger than the sum of its proper divisors (15719).

6855781 is a wasteful number, since it uses less digits than its factorization.

6855781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15718.

The product of its digits is 67200, while the sum is 40.

The square root of 6855781 is about 2618.3546360262. The cubic root of 6855781 is about 189.9702723573.

The spelling of 6855781 in words is "six million, eight hundred fifty-five thousand, seven hundred eighty-one".