7991111998 has 8 divisors (see below), whose sum is σ = 12617545320. Its totient is φ = 3785263560.

The previous prime is 7991111993. The next prime is 7991112007. The reversal of 7991111998 is 8991111997.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7991111993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 105146173 + ... + 105146248.

It is an arithmetic number, because the mean of its divisors is an integer number (1577193165).

Almost surely, 2^7991111998 is an apocalyptic number.

7991111998 is a deficient number, since it is larger than the sum of its proper divisors (4626433322).

7991111998 is a wasteful number, since it uses less digits than its factorization.

7991111998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 210292442.

The product of its digits is 367416, while the sum is 55.

The square root of 7991111998 is about 89393.0198505454. The cubic root of 7991111998 is about 1999.2590587036.

Subtracting 7991111998 from its reverse (8991111997), we obtain a palindrome (999999999).

The spelling of 7991111998 in words is "seven billion, nine hundred ninety-one million, one hundred eleven thousand, nine hundred ninety-eight".