6781321 has 2 divisors, whose sum is σ = 6781322. Its totient is φ = 6781320.

The previous prime is 6781319. The next prime is 6781337. The reversal of 6781321 is 1231876.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6702921 + 78400 = 2589^2 + 280^2 .

It is a cyclic number.

It is not a de Polignac number, because 6781321 - 2¹ = 6781319 is a prime.

Together with 6781319, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 6781321.

It is not a weakly prime, because it can be changed into another prime (6781381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3390660 + 3390661.

It is an arithmetic number, because the mean of its divisors is an integer number (3390661).

Almost surely, 2^6781321 is an apocalyptic number.

It is an amenable number.

6781321 is a deficient number, since it is larger than the sum of its proper divisors (1).

6781321 is an equidigital number, since it uses as much as digits as its factorization.

6781321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2016, while the sum is 28.

The square root of 6781321 is about 2604.0969644005. The cubic root of 6781321 is about 189.2800175403.

The spelling of 6781321 in words is "six million, seven hundred eighty-one thousand, three hundred twenty-one".