1991004 has 24 divisors (see below), whose sum is σ = 4704000. Its totient is φ = 655344.

The previous prime is 1990987. The next prime is 1991027. The reversal of 1991004 is 4001991.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4 + ... + 1995.

It is an arithmetic number, because the mean of its divisors is an integer number (196000).

2^1991004 is an apocalyptic number.

It is an amenable number.

1991004 is an abundant number, since it is smaller than the sum of its proper divisors (2712996).

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

1991004 is a wasteful number, since it uses less digits than its factorization.

1991004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2089 (or 2087 counting only the distinct ones).

The product of its (nonzero) digits is 324, while the sum is 24.

The square root of 1991004 is about 1411.0294114582. The cubic root of 1991004 is about 125.8029168865.

Adding to 1991004 its reverse (4001991), we get a palindrome (5992995).

The spelling of 1991004 in words is "one million, nine hundred ninety-one thousand, four".