991000000198 has 16 divisors (see below), whose sum is σ = 1602659154096. Its totient is φ = 456866615520.

The previous prime is 991000000181. The next prime is 991000000201. The reversal of 991000000198 is 891000000199.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21559933 + ... + 21605848.

It is an arithmetic number, because the mean of its divisors is an integer number (100166197131).

Almost surely, 2^991000000198 is an apocalyptic number.

991000000198 is a deficient number, since it is larger than the sum of its proper divisors (611659153898).

991000000198 is a wasteful number, since it uses less digits than its factorization.

991000000198 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43166679.

The product of its (nonzero) digits is 5832, while the sum is 37.

Subtracting from 991000000198 its reverse (891000000199), we obtain a palindrome (99999999999).

The spelling of 991000000198 in words is "nine hundred ninety-one billion, one hundred ninety-eight", and thus it is an aban number.