1991149 has 4 divisors (see below), whose sum is σ = 1995964. Its totient is φ = 1986336.

The previous prime is 1991147. The next prime is 1991153. The reversal of 1991149 is 9411991.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9411991 = 23 ⋅409217.

It can be written as a sum of positive squares in 2 ways, for example, as 1909924 + 81225 = 1382^2 + 285^2 .

It is a cyclic number.

It is not a de Polignac number, because 1991149 - 2¹ = 1991147 is a prime.

It is a Duffinian number.

1991149 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991147) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1722 + ... + 2635.

It is an arithmetic number, because the mean of its divisors is an integer number (498991).

2^1991149 is an apocalyptic number.

It is an amenable number.

1991149 is a deficient number, since it is larger than the sum of its proper divisors (4815).

1991149 is an equidigital number, since it uses as much as digits as its factorization.

1991149 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4814.

The product of its digits is 2916, while the sum is 34.

The square root of 1991149 is about 1411.0807914503. The cubic root of 1991149 is about 125.8059707863.

The spelling of 1991149 in words is "one million, nine hundred ninety-one thousand, one hundred forty-nine".