991199 has 8 divisors (see below), whose sum is σ = 1088640. Its totient is φ = 895000.

The previous prime is 991187. The next prime is 991201.

It is a happy number.

991199 is nontrivially palindromic in base 10.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 991199 - 2¹⁶ = 925663 is a prime.

It is a Duffinian number.

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 (991129) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2582 + ... + 2940.

It is an arithmetic number, because the mean of its divisors is an integer number (136080).

2⁹⁹¹¹⁹⁹ is an apocalyptic number.

991199 is a deficient number, since it is larger than the sum of its proper divisors (97441).

991199 is a wasteful number, since it uses less digits than its factorization.

991199 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 621.

The product of its digits is 6561, while the sum is 38.

The square root of 991199 is about 995.5897749575. The cubic root of 991199 is about 99.7057684604.

It can be divided in two parts, 9911 and 99, that multiplied together give a palindrome (981189).

The spelling of 991199 in words is "nine hundred ninety-one thousand, one hundred ninety-nine".