1774728661891 has 2 divisors, whose sum is σ = 1774728661892. Its totient is φ = 1774728661890.

The previous prime is 1774728661889. The next prime is 1774728661957. The reversal of 1774728661891 is 1981668274771.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1774728661891 - 2¹ = 1774728661889 is a prime.

Together with 1774728661889, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1774728661831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 887364330945 + 887364330946.

It is an arithmetic number, because the mean of its divisors is an integer number (887364330946).

Almost surely, 2^{1774728661891} is an apocalyptic number.

1774728661891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1774728661891 is an equidigital number, since it uses as much as digits as its factorization.

1774728661891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 56899584, while the sum is 67.

The spelling of 1774728661891 in words is "one trillion, seven hundred seventy-four billion, seven hundred twenty-eight million, six hundred sixty-one thousand, eight hundred ninety-one".