1991799 has 6 divisors (see below), whose sum is σ = 2877056. Its totient is φ = 1327860.

The previous prime is 1991797. The next prime is 1991819. The reversal of 1991799 is 9971991.

It is not a de Polignac number, because 1991799 - 2¹ = 1991797 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 (1991797) 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 5 ways as a sum of consecutive naturals, for example, 110647 + ... + 110664.

2^1991799 is an apocalyptic number.

1991799 is a deficient number, since it is larger than the sum of its proper divisors (885257).

1991799 is a wasteful number, since it uses less digits than its factorization.

1991799 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 221317 (or 221314 counting only the distinct ones).

The product of its digits is 45927, while the sum is 45.

The square root of 1991799 is about 1411.3110925661. The cubic root of 1991799 is about 125.8196588603.

The spelling of 1991799 in words is "one million, nine hundred ninety-one thousand, seven hundred ninety-nine".