1991327328 has 60 divisors (see below), whose sum is σ = 5856445980. Its totient is φ = 663774912.

The previous prime is 1991327323. The next prime is 1991327347. The reversal of 1991327328 is 8237231991.

1991327328 is a `hidden beast` number, since 199 + 132 + 7 + 328 = 666.

1991327328 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991327321) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 381538 + ... + 386721.

It is an arithmetic number, because the mean of its divisors is an integer number (97607433).

Almost surely, 2^1991327328 is an apocalyptic number.

1991327328 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

1991327328 is an abundant number, since it is smaller than the sum of its proper divisors (3865118652).

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

1991327328 is an equidigital number, since it uses as much as digits as its factorization.

1991327328 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 768281 (or 768264 counting only the distinct ones).

The product of its digits is 163296, while the sum is 45.

The square root of 1991327328 is about 44624.2907842803. The cubic root of 1991327328 is about 1258.0972641645.

The spelling of 1991327328 in words is "one billion, nine hundred ninety-one million, three hundred twenty-seven thousand, three hundred twenty-eight".