328991 has 4 divisors (see below), whose sum is σ = 354312. Its totient is φ = 303672.

The previous prime is 328981. The next prime is 329009. The reversal of 328991 is 199823.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 328991 - 2¹⁰ = 327967 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 (328901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12641 + ... + 12666.

It is an arithmetic number, because the mean of its divisors is an integer number (88578).

2³²⁸⁹⁹¹ is an apocalyptic number.

328991 is a deficient number, since it is larger than the sum of its proper divisors (25321).

328991 is a wasteful number, since it uses less digits than its factorization.

328991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25320.

The product of its digits is 3888, while the sum is 32.

The square root of 328991 is about 573.5773705439. The cubic root of 328991 is about 69.0337299206.

The spelling of 328991 in words is "three hundred twenty-eight thousand, nine hundred ninety-one".