6678821 has 4 divisors (see below), whose sum is σ = 6690432. Its totient is φ = 6667212.

The previous prime is 6678817. The next prime is 6678839. The reversal of 6678821 is 1288766.

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: 1288766 = 2 ⋅644383.

It is a cyclic number.

It is not a de Polignac number, because 6678821 - 2² = 6678817 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6678851) 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, 4895 + ... + 6108.

It is an arithmetic number, because the mean of its divisors is an integer number (1672608).

Almost surely, 2^6678821 is an apocalyptic number.

It is an amenable number.

6678821 is a deficient number, since it is larger than the sum of its proper divisors (11611).

6678821 is a wasteful number, since it uses less digits than its factorization.

6678821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11610.

The product of its digits is 32256, while the sum is 38.

The square root of 6678821 is about 2584.3415022013. The cubic root of 6678821 is about 188.3215129937.

It can be divided in two parts, 66 and 78821, that added together give a palindrome (78887).

The spelling of 6678821 in words is "six million, six hundred seventy-eight thousand, eight hundred twenty-one".