1943381911981 has 2 divisors, whose sum is σ = 1943381911982. Its totient is φ = 1943381911980.

The previous prime is 1943381911931. The next prime is 1943381912039. The reversal of 1943381911981 is 1891191833491.

It is an a-pointer prime, because the next prime (1943381912039) can be obtained adding 1943381911981 to its sum of digits (58).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1701091539081 + 242290372900 = 1304259^2 + 492230^2 .

It is a cyclic number.

It is not a de Polignac number, because 1943381911981 - 2⁷ = 1943381911853 is a prime.

It is a super-2 number, since 2×1943381911981² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1943381911931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 971690955990 + 971690955991.

It is an arithmetic number, because the mean of its divisors is an integer number (971690955991).

Almost surely, 2^{1943381911981} is an apocalyptic number.

It is an amenable number.

1943381911981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1943381911981 is an equidigital number, since it uses as much as digits as its factorization.

1943381911981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1679616, while the sum is 58.

The spelling of 1943381911981 in words is "one trillion, nine hundred forty-three billion, three hundred eighty-one million, nine hundred eleven thousand, nine hundred eighty-one".