1991104 has 28 divisors (see below), whose sum is σ = 4032504. Its totient is φ = 975104.

The previous prime is 1991089. The next prime is 1991107. The reversal of 1991104 is 4011991.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991107) 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, 3099 + ... + 3685.

It is an arithmetic number, because the mean of its divisors is an integer number (144018).

2^1991104 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1991104, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2016252).

1991104 is an abundant number, since it is smaller than the sum of its proper divisors (2041400).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1991104 is an equidigital number, since it uses as much as digits as its factorization.

1991104 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 652 (or 642 counting only the distinct ones).

The product of its (nonzero) digits is 324, while the sum is 25.

The square root of 1991104 is about 1411.0648461357. The cubic root of 1991104 is about 125.8050230402.

The spelling of 1991104 in words is "one million, nine hundred ninety-one thousand, one hundred four".