161863818108991 has 2 divisors, whose sum is σ = 161863818108992. Its totient is φ = 161863818108990.

The previous prime is 161863818108959. The next prime is 161863818109061. The reversal of 161863818108991 is 199801818368161.

It is an a-pointer prime, because the next prime (161863818109061) can be obtained adding 161863818108991 to its sum of digits (70).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 161863818108991 - 2⁵ = 161863818108959 is a prime.

It is a super-2 number, since 2×161863818108991² (a number of 29 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 161863818108991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161863818108901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80931909054495 + 80931909054496.

It is an arithmetic number, because the mean of its divisors is an integer number (80931909054496).

Almost surely, 2^{161863818108991} is an apocalyptic number.

161863818108991 is a deficient number, since it is larger than the sum of its proper divisors (1).

161863818108991 is an equidigital number, since it uses as much as digits as its factorization.

161863818108991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 35831808, while the sum is 70.

The spelling of 161863818108991 in words is "one hundred sixty-one trillion, eight hundred sixty-three billion, eight hundred eighteen million, one hundred eight thousand, nine hundred ninety-one".