6810781 has 4 divisors (see below), whose sum is σ = 6817312. Its totient is φ = 6804252.

The previous prime is 6810779. The next prime is 6810799. The reversal of 6810781 is 1870186.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1870186 = 2 ⋅935093.

It is a cyclic number.

It is not a de Polignac number, because 6810781 - 2¹ = 6810779 is a prime.

It is a super-2 number, since 2×6810781² = 92773475659922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6810281) 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, 1311 + ... + 3916.

It is an arithmetic number, because the mean of its divisors is an integer number (1704328).

Almost surely, 2^6810781 is an apocalyptic number.

It is an amenable number.

6810781 is a deficient number, since it is larger than the sum of its proper divisors (6531).

6810781 is a wasteful number, since it uses less digits than its factorization.

6810781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6530.

The product of its (nonzero) digits is 2688, while the sum is 31.

The square root of 6810781 is about 2609.7473057750. The cubic root of 6810781 is about 189.5537171088.

The spelling of 6810781 in words is "six million, eight hundred ten thousand, seven hundred eighty-one".