309985 has 16 divisors (see below), whose sum is σ = 423360. Its totient is φ = 216000.

The previous prime is 309977. The next prime is 309989. The reversal of 309985 is 589903.

309985 is nontrivially palindromic in base 4.

It is not a de Polignac number, because 309985 - 2³ = 309977 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 309985.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 309985.

It is not an unprimeable number, because it can be changed into a prime (309989) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1110 + ... + 1360.

It is an arithmetic number, because the mean of its divisors is an integer number (26460).

2³⁰⁹⁹⁸⁵ is an apocalyptic number.

It is an amenable number.

309985 is a deficient number, since it is larger than the sum of its proper divisors (113375).

309985 is a wasteful number, since it uses less digits than its factorization.

309985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 288.

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

The square root of 309985 is about 556.7629657224. The cubic root of 309985 is about 67.6779029068.

The spelling of 309985 in words is "three hundred nine thousand, nine hundred eighty-five".