1099999999981 has 2 divisors, whose sum is σ = 1099999999982. Its totient is φ = 1099999999980.

The previous prime is 1099999999961. The next prime is 1099999999999. The reversal of 1099999999981 is 1899999999901.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 934953624900 + 165046375081 = 966930^2 + 406259^2 .

It is an emirp because it is prime and its reverse (1899999999901) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1099999999981 - 2¹¹ = 1099999997933 is a prime.

It is a super-2 number, since 2×1099999999981² (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 (1099999999961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 549999999990 + 549999999991.

It is an arithmetic number, because the mean of its divisors is an integer number (549999999991).

Almost surely, 2^{1099999999981} is an apocalyptic number.

It is an amenable number.

1099999999981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1099999999981 is an equidigital number, since it uses as much as digits as its factorization.

1099999999981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3099363912, while the sum is 91.

The spelling of 1099999999981 in words is "one trillion, ninety-nine billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred eighty-one".