1981463378981 has 2 divisors, whose sum is σ = 1981463378982. Its totient is φ = 1981463378980.

The previous prime is 1981463378963. The next prime is 1981463379013. The reversal of 1981463378981 is 1898733641891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1869328810756 + 112134568225 = 1367234^2 + 334865^2 .

It is a cyclic number.

It is not a de Polignac number, because 1981463378981 - 2¹⁸ = 1981463116837 is a prime.

It is a super-3 number, since 3×1981463378981³ (a number of 38 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1981463378941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 990731689490 + 990731689491.

It is an arithmetic number, because the mean of its divisors is an integer number (990731689491).

Almost surely, 2^{1981463378981} is an apocalyptic number.

It is an amenable number.

1981463378981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1981463378981 is an equidigital number, since it uses as much as digits as its factorization.

1981463378981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 62705664, while the sum is 68.

The spelling of 1981463378981 in words is "one trillion, nine hundred eighty-one billion, four hundred sixty-three million, three hundred seventy-eight thousand, nine hundred eighty-one".