6781737921691 has 2 divisors, whose sum is σ = 6781737921692. Its totient is φ = 6781737921690.

The previous prime is 6781737921677. The next prime is 6781737921697. The reversal of 6781737921691 is 1961297371876.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 6781737921691 - 2⁵ = 6781737921659 is a prime.

It is not a weakly prime, because it can be changed into another prime (6781737921697) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3390868960845 + 3390868960846.

It is an arithmetic number, because the mean of its divisors is an integer number (3390868960846).

Almost surely, 2^{6781737921691} is an apocalyptic number.

6781737921691 is a deficient number, since it is larger than the sum of its proper divisors (1).

6781737921691 is an equidigital number, since it uses as much as digits as its factorization.

6781737921691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48009024, while the sum is 67.

The spelling of 6781737921691 in words is "six trillion, seven hundred eighty-one billion, seven hundred thirty-seven million, nine hundred twenty-one thousand, six hundred ninety-one".