991139218911 has 24 divisors (see below), whose sum is σ = 1465007303760. Its totient is φ = 645363161856.

The previous prime is 991139218903. The next prime is 991139218919. The reversal of 991139218911 is 119812931199.

It is an interprime number because it is at equal distance from previous prime (991139218903) and next prime (991139218919).

It is not a de Polignac number, because 991139218911 - 2³ = 991139218903 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991139218919) 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 23 ways as a sum of consecutive naturals, for example, 10991175 + ... + 11080983.

It is an arithmetic number, because the mean of its divisors is an integer number (61041970990).

Almost surely, 2^991139218911 is an apocalyptic number.

991139218911 is a deficient number, since it is larger than the sum of its proper divisors (473868084849).

991139218911 is a wasteful number, since it uses less digits than its factorization.

991139218911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118375 (or 118372 counting only the distinct ones).

The product of its digits is 314928, while the sum is 54.

The spelling of 991139218911 in words is "nine hundred ninety-one billion, one hundred thirty-nine million, two hundred eighteen thousand, nine hundred eleven".