991123 has 12 divisors (see below), whose sum is σ = 1169640. Its totient is φ = 837312.

The previous prime is 991091. The next prime is 991127. The reversal of 991123 is 321199.

It is not a de Polignac number, because 991123 - 2⁵ = 991091 is a prime.

It is a super-2 number, since 2×991123² = 1964649602258, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (991127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5448 + ... + 5626.

It is an arithmetic number, because the mean of its divisors is an integer number (97470).

2⁹⁹¹¹²³ is an apocalyptic number.

991123 is a deficient number, since it is larger than the sum of its proper divisors (178517).

991123 is a wasteful number, since it uses less digits than its factorization.

991123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 306 (or 299 counting only the distinct ones).

The product of its digits is 486, while the sum is 25.

The square root of 991123 is about 995.5516058949. The cubic root of 991123 is about 99.7032200882.

The spelling of 991123 in words is "nine hundred ninety-one thousand, one hundred twenty-three".