11109991 has 4 divisors (see below), whose sum is σ = 11292184. Its totient is φ = 10927800.

The previous prime is 11109983. The next prime is 11110031. The reversal of 11109991 is 19990111.

11109991 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.

It is a cyclic number.

It is not a de Polignac number, because 11109991 - 2³ = 11109983 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 (11109941) 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, 91005 + ... + 91126.

It is an arithmetic number, because the mean of its divisors is an integer number (2823046).

Almost surely, 2^11109991 is an apocalyptic number.

11109991 is a deficient number, since it is larger than the sum of its proper divisors (182193).

11109991 is an equidigital number, since it uses as much as digits as its factorization.

11109991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 182192.

The product of its (nonzero) digits is 729, while the sum is 31.

The square root of 11109991 is about 3333.1653124320. The cubic root of 11109991 is about 223.1368180492.

It can be divided in two parts, 11109 and 991, that added together give a square (12100 = 110²).

The spelling of 11109991 in words is "eleven million, one hundred nine thousand, nine hundred ninety-one".