999981999991 has 8 divisors (see below), whose sum is σ = 1092071350944. Its totient is φ = 910059457440.

The previous prime is 999981999983. The next prime is 999982000009. The reversal of 999981999991 is 199999189999.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 999981999991 - 2³ = 999981999983 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 999981999896 and 999981999905.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999981999971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 541701136 + ... + 541702981.

It is an arithmetic number, because the mean of its divisors is an integer number (136508918868).

Almost surely, 2^999981999991 is an apocalyptic number.

999981999991 is a deficient number, since it is larger than the sum of its proper divisors (92089350953).

999981999991 is a wasteful number, since it uses less digits than its factorization.

999981999991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1083404201.

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

The spelling of 999981999991 in words is "nine hundred ninety-nine billion, nine hundred eighty-one million, nine hundred ninety-nine thousand, nine hundred ninety-one".