6781843921 has 2 divisors, whose sum is σ = 6781843922. Its totient is φ = 6781843920.

The previous prime is 6781843903. The next prime is 6781843951. The reversal of 6781843921 is 1293481876.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4059091521 + 2722752400 = 63711^2 + 52180^2 .

It is a cyclic number.

It is not a de Polignac number, because 6781843921 - 2⁵ = 6781843889 is a prime.

It is not a weakly prime, because it can be changed into another prime (6781843951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3390921960 + 3390921961.

It is an arithmetic number, because the mean of its divisors is an integer number (3390921961).

Almost surely, 2^6781843921 is an apocalyptic number.

It is an amenable number.

6781843921 is a deficient number, since it is larger than the sum of its proper divisors (1).

6781843921 is an equidigital number, since it uses as much as digits as its factorization.

6781843921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 580608, while the sum is 49.

The square root of 6781843921 is about 82351.9515312175. The cubic root of 6781843921 is about 1892.8488266676.

The spelling of 6781843921 in words is "six billion, seven hundred eighty-one million, eight hundred forty-three thousand, nine hundred twenty-one".