991111111222 has 4 divisors (see below), whose sum is σ = 1486666666836. Its totient is φ = 495555555610.

The previous prime is 991111111213. The next prime is 991111111229. The reversal of 991111111222 is 222111111199.

991111111222 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 222111111199 = 53 ⋅4190775683.

It is a zygodrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991111111229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 247777777804 + ... + 247777777807.

It is an arithmetic number, because the mean of its divisors is an integer number (371666666709).

Almost surely, 2^991111111222 is an apocalyptic number.

991111111222 is a deficient number, since it is larger than the sum of its proper divisors (495555555614).

991111111222 is a wasteful number, since it uses less digits than its factorization.

991111111222 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 495555555613.

The product of its digits is 648, while the sum is 31.

The spelling of 991111111222 in words is "nine hundred ninety-one billion, one hundred eleven million, one hundred eleven thousand, two hundred twenty-two".