309505 has 16 divisors (see below), whose sum is σ = 437760. Its totient is φ = 205632.

The previous prime is 309503. The next prime is 309521. The reversal of 309505 is 505903.

It is not a de Polignac number, because 309505 - 2¹ = 309503 is a prime.

309505 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (309503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1176 + ... + 1414.

It is an arithmetic number, because the mean of its divisors is an integer number (27360).

2³⁰⁹⁵⁰⁵ is an apocalyptic number.

309505 is a gapful number since it is divisible by the number (35) formed by its first and last digit.

It is an amenable number.

309505 is a deficient number, since it is larger than the sum of its proper divisors (128255).

309505 is a wasteful number, since it uses less digits than its factorization.

309505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 288.

The product of its (nonzero) digits is 675, while the sum is 22.

The square root of 309505 is about 556.3317355679. The cubic root of 309505 is about 67.6429526400.

The spelling of 309505 in words is "three hundred nine thousand, five hundred five".