991198118911 has 72 divisors (see below), whose sum is σ = 1367541684432. Its totient is φ = 711552441600.

The previous prime is 991198118909. The next prime is 991198118959. The reversal of 991198118911 is 119811891199.

991198118911 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 991198118911 - 2¹ = 991198118909 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991198118011) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 40144776 + ... + 40169458.

It is an arithmetic number, because the mean of its divisors is an integer number (18993634506).

Almost surely, 2^991198118911 is an apocalyptic number.

991198118911 is a gapful number since it is divisible by the number (91) formed by its first and last digit.

991198118911 is a deficient number, since it is larger than the sum of its proper divisors (376343565521).

991198118911 is a wasteful number, since it uses less digits than its factorization.

991198118911 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25253 (or 25235 counting only the distinct ones).

The product of its digits is 419904, while the sum is 58.

The spelling of 991198118911 in words is "nine hundred ninety-one billion, one hundred ninety-eight million, one hundred eighteen thousand, nine hundred eleven".