19877889881891 has 2 divisors, whose sum is σ = 19877889881892. Its totient is φ = 19877889881890.

The previous prime is 19877889881881. The next prime is 19877889881953. The reversal of 19877889881891 is 19818898877891.

It is a weak prime.

It is an emirp because it is prime and its reverse (19818898877891) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19877889881891 - 2³⁰ = 19876816140067 is a prime.

It is a Sophie Germain prime.

It is a self number, because there is not a number n which added to its sum of digits gives 19877889881891.

It is not a weakly prime, because it can be changed into another prime (19877889881821) 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, 9938944940945 + 9938944940946.

It is an arithmetic number, because the mean of its divisors is an integer number (9938944940946).

Almost surely, 2^{19877889881891} is an apocalyptic number.

19877889881891 is a deficient number, since it is larger than the sum of its proper divisors (1).

19877889881891 is an equidigital number, since it uses as much as digits as its factorization.

19877889881891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9364045824, while the sum is 92.

The spelling of 19877889881891 in words is "nineteen trillion, eight hundred seventy-seven billion, eight hundred eighty-nine million, eight hundred eighty-one thousand, eight hundred ninety-one".