309218 has 16 divisors (see below), whose sum is σ = 571200. Its totient is φ = 122256.

The previous prime is 309193. The next prime is 309223. The reversal of 309218 is 812903.

It is an alternating number because its digits alternate between odd and even.

It is a Curzon number.

It is a nialpdrome in base 13.

It is a junction number, because it is equal to n+sod(n) for n = 309193 and 309202.

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 309218.

It is an unprimeable number.

309218 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 668 + ... + 1031.

It is an arithmetic number, because the mean of its divisors is an integer number (35700).

2³⁰⁹²¹⁸ is an apocalyptic number.

309218 is a deficient number, since it is larger than the sum of its proper divisors (261982).

309218 is a wasteful number, since it uses less digits than its factorization.

309218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1721.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 309218 is about 556.0737361178. The cubic root of 309218 is about 67.6220380279.

The spelling of 309218 in words is "three hundred nine thousand, two hundred eighteen".