991199111 has 8 divisors (see below), whose sum is σ = 1134487584. Its totient is φ = 848332800.

The previous prime is 991199081. The next prime is 991199117. The reversal of 991199111 is 111991199.

It is a happy number.

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

It is not a de Polignac number, because 991199111 - 2²² = 987004807 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 (991199117) 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, 100490 + ... + 109911.

It is an arithmetic number, because the mean of its divisors is an integer number (141810948).

Almost surely, 2^991199111 is an apocalyptic number.

991199111 is a deficient number, since it is larger than the sum of its proper divisors (143288473).

991199111 is a wasteful number, since it uses less digits than its factorization.

991199111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 211081.

The product of its digits is 6561, while the sum is 41.

The square root of 991199111 is about 31483.3148032414. The cubic root of 991199111 is about 997.0577218229.

The spelling of 991199111 in words is "nine hundred ninety-one million, one hundred ninety-nine thousand, one hundred eleven".