309216 has 24 divisors (see below), whose sum is σ = 811944. Its totient is φ = 103040.

The previous prime is 309193. The next prime is 309223. The reversal of 309216 is 612903.

It is a tau number, because it is divible by the number of its divisors (24).

It is a super-2 number, since 2×309216² = 191229069312, which contains 22 as substring.

It is a Smith number, since the sum of its digits (21) coincides with the sum of the digits of its prime factors.

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

It is a junction number, because it is equal to n+sod(n) for n = 309192 and 309201.

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 309216.

It is an unprimeable number.

309216 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1515 + ... + 1706.

It is an arithmetic number, because the mean of its divisors is an integer number (33831).

2³⁰⁹²¹⁶ is an apocalyptic number.

It is an amenable number.

309216 is an abundant number, since it is smaller than the sum of its proper divisors (502728).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

309216 is a wasteful number, since it uses less digits than its factorization.

309216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3234 (or 3226 counting only the distinct ones).

The product of its (nonzero) digits is 324, while the sum is 21.

The square root of 309216 is about 556.0719377922. The cubic root of 309216 is about 67.6218922360.

It can be divided in two parts, 309 and 216, that added together give a palindrome (525).

The spelling of 309216 in words is "three hundred nine thousand, two hundred sixteen".