1981003681 has 2 divisors, whose sum is σ = 1981003682. Its totient is φ = 1981003680.

The previous prime is 1981003663. The next prime is 1981003699. The reversal of 1981003681 is 1863001891.

It is a balanced prime because it is at equal distance from previous prime (1981003663) and next prime (1981003699).

It can be written as a sum of positive squares in only one way, i.e., 1163901456 + 817102225 = 34116^2 + 28585^2 .

It is a cyclic number.

It is not a de Polignac number, because 1981003681 - 2¹⁹ = 1980479393 is a prime.

It is a super-3 number, since 3×1981003681³ (a number of 29 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a self number, because there is not a number n which added to its sum of digits gives 1981003681.

It is not a weakly prime, because it can be changed into another prime (1981003181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 990501840 + 990501841.

It is an arithmetic number, because the mean of its divisors is an integer number (990501841).

Almost surely, 2^1981003681 is an apocalyptic number.

It is an amenable number.

1981003681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1981003681 is an equidigital number, since it uses as much as digits as its factorization.

1981003681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10368, while the sum is 37.

The square root of 1981003681 is about 44508.4675202371. The cubic root of 1981003681 is about 1255.9193764850.

The spelling of 1981003681 in words is "one billion, nine hundred eighty-one million, three thousand, six hundred eighty-one".