6806821 has 4 divisors (see below), whose sum is σ = 7779232. Its totient is φ = 5834412.

The previous prime is 6806803. The next prime is 6806831. The reversal of 6806821 is 1286086.

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 an emirpimes, since its reverse is a distinct semiprime: 1286086 = 2 ⋅643043.

It is a cyclic number.

It is not a de Polignac number, because 6806821 - 2⁹ = 6806309 is a prime.

It is a Duffinian number.

6806821 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6806801) 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, 486195 + ... + 486208.

It is an arithmetic number, because the mean of its divisors is an integer number (1944808).

Almost surely, 2^6806821 is an apocalyptic number.

It is an amenable number.

6806821 is a deficient number, since it is larger than the sum of its proper divisors (972411).

6806821 is an equidigital number, since it uses as much as digits as its factorization.

6806821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 972410.

The product of its (nonzero) digits is 4608, while the sum is 31.

The square root of 6806821 is about 2608.9885013162. The cubic root of 6806821 is about 189.5169725100.

The spelling of 6806821 in words is "six million, eight hundred six thousand, eight hundred twenty-one".