1991328 has 24 divisors (see below), whose sum is σ = 5227488. Its totient is φ = 663744.

The previous prime is 1991293. The next prime is 1991351. The reversal of 1991328 is 8231991.

It is a tau number, because it is divible by the number of its divisors (24).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10276 + ... + 10467.

It is an arithmetic number, because the mean of its divisors is an integer number (217812).

2^1991328 is an apocalyptic number.

It is an amenable number.

1991328 is an abundant number, since it is smaller than the sum of its proper divisors (3236160).

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

1991328 is a wasteful number, since it uses less digits than its factorization.

1991328 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20756 (or 20748 counting only the distinct ones).

The product of its digits is 3888, while the sum is 33.

The square root of 1991328 is about 1411.1442165845. The cubic root of 1991328 is about 125.8097405685.

The spelling of 1991328 in words is "one million, nine hundred ninety-one thousand, three hundred twenty-eight".