308991 has 8 divisors (see below), whose sum is σ = 415744. Its totient is φ = 204120.

The previous prime is 308989. The next prime is 308999. The reversal of 308991 is 199803.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 308991 - 2¹ = 308989 is a prime.

It is a Duffinian number.

It is a plaindrome in base 8.

It is a zygodrome in base 8.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 308991.

It is not an unprimeable number, because it can be changed into a prime (308999) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25 + ... + 786.

It is an arithmetic number, because the mean of its divisors is an integer number (51968).

2³⁰⁸⁹⁹¹ is an apocalyptic number.

308991 is a deficient number, since it is larger than the sum of its proper divisors (106753).

308991 is a wasteful number, since it uses less digits than its factorization.

308991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 941.

The product of its (nonzero) digits is 1944, while the sum is 30.

The square root of 308991 is about 555.8695890225. The cubic root of 308991 is about 67.6054866408.

The spelling of 308991 in words is "three hundred eight thousand, nine hundred ninety-one".