6818921 has 4 divisors (see below), whose sum is σ = 7220052. Its totient is φ = 6417792.

The previous prime is 6818899. The next prime is 6818939. The reversal of 6818921 is 1298186.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1298186 = 2 ⋅649093.

It can be written as a sum of positive squares in 2 ways, for example, as 5221225 + 1597696 = 2285^2 + 1264^2 .

It is a cyclic number.

It is not a de Polignac number, because 6818921 - 2¹⁰ = 6817897 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (6818941) 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, 200540 + ... + 200573.

It is an arithmetic number, because the mean of its divisors is an integer number (1805013).

Almost surely, 2^6818921 is an apocalyptic number.

It is an amenable number.

6818921 is a deficient number, since it is larger than the sum of its proper divisors (401131).

6818921 is a wasteful number, since it uses less digits than its factorization.

6818921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 401130.

The product of its digits is 6912, while the sum is 35.

The square root of 6818921 is about 2611.3063780415. The cubic root of 6818921 is about 189.6292029680.

The spelling of 6818921 in words is "six million, eight hundred eighteen thousand, nine hundred twenty-one".