1091905 has 4 divisors (see below), whose sum is σ = 1310292. Its totient is φ = 873520.

The previous prime is 1091887. The next prime is 1091917. The reversal of 1091905 is 5091901.

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

It can be written as a sum of positive squares in 2 ways, for example, as 804609 + 287296 = 897^2 + 536^2 .

It is not a de Polignac number, because 1091905 - 2⁷ = 1091777 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1091905.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 109186 + ... + 109195.

It is an arithmetic number, because the mean of its divisors is an integer number (327573).

2^1091905 is an apocalyptic number.

It is an amenable number.

1091905 is a deficient number, since it is larger than the sum of its proper divisors (218387).

1091905 is an equidigital number, since it uses as much as digits as its factorization.

1091905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218386.

The product of its (nonzero) digits is 405, while the sum is 25.

The square root of 1091905 is about 1044.9425821546. The cubic root of 1091905 is about 102.9741663933.

The spelling of 1091905 in words is "one million, ninety-one thousand, nine hundred five".