1109991 has 4 divisors (see below), whose sum is σ = 1479992. Its totient is φ = 739992.

The previous prime is 1109987. The next prime is 1110007. The reversal of 1109991 is 1999011.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1109991 - 2² = 1109987 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1109921) 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, 184996 + ... + 185001.

It is an arithmetic number, because the mean of its divisors is an integer number (369998).

2^1109991 is an apocalyptic number.

1109991 is a deficient number, since it is larger than the sum of its proper divisors (370001).

1109991 is an equidigital number, since it uses as much as digits as its factorization.

1109991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 370000.

The product of its (nonzero) digits is 729, while the sum is 30.

The square root of 1109991 is about 1053.5611040656. The cubic root of 1109991 is about 103.5396007066.

It can be divided in two parts, 110 and 9991, that added together give a palindrome (10101).

The spelling of 1109991 in words is "one million, one hundred nine thousand, nine hundred ninety-one".