305989 has 4 divisors (see below), whose sum is σ = 310624. Its totient is φ = 301356.

The previous prime is 305971. The next prime is 305999. The reversal of 305989 is 989503.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 989503 = 151 ⋅6553.

It is a cyclic number.

It is not a de Polignac number, because 305989 - 2⁷ = 305861 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 (305999) 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, 2217 + ... + 2350.

It is an arithmetic number, because the mean of its divisors is an integer number (77656).

2³⁰⁵⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

305989 is a deficient number, since it is larger than the sum of its proper divisors (4635).

305989 is an equidigital number, since it uses as much as digits as its factorization.

305989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4634.

The product of its (nonzero) digits is 9720, while the sum is 34.

The square root of 305989 is about 553.1627247022. The cubic root of 305989 is about 67.3858335332.

The spelling of 305989 in words is "three hundred five thousand, nine hundred eighty-nine".