991111223 has 4 divisors (see below), whose sum is σ = 1005070608. Its totient is φ = 977151840.

The previous prime is 991111213. The next prime is 991111229. The reversal of 991111223 is 322111199.

991111223 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: 322111199 = 19 ⋅16953221.

It is a cyclic number.

It is not a de Polignac number, because 991111223 - 2⁶ = 991111159 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991111229) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6979586 + ... + 6979727.

It is an arithmetic number, because the mean of its divisors is an integer number (251267652).

Almost surely, 2^991111223 is an apocalyptic number.

991111223 is a deficient number, since it is larger than the sum of its proper divisors (13959385).

991111223 is a wasteful number, since it uses less digits than its factorization.

991111223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13959384.

The product of its digits is 972, while the sum is 29.

The square root of 991111223 is about 31481.9189853478. The cubic root of 991111223 is about 997.0282517941.

The spelling of 991111223 in words is "nine hundred ninety-one million, one hundred eleven thousand, two hundred twenty-three".