243312309 has 32 divisors (see below), whose sum is σ = 385152000. Its totient is φ = 151355952.

The previous prime is 243312301. The next prime is 243312317. The reversal of 243312309 is 903213342.

It is a happy number.

243312309 is a `hidden beast` number, since 2 + 43 + 312 + 309 = 666.

It is an interprime number because it is at equal distance from previous prime (243312301) and next prime (243312317).

It is not a de Polignac number, because 243312309 - 2³ = 243312301 is a prime.

It is a super-2 number, since 2×243312309² = 118401759421822962, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (243312301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 30832 + ... + 37910.

It is an arithmetic number, because the mean of its divisors is an integer number (12036000).

Almost surely, 2^243312309 is an apocalyptic number.

It is an amenable number.

243312309 is a deficient number, since it is larger than the sum of its proper divisors (141839691).

243312309 is a wasteful number, since it uses less digits than its factorization.

243312309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7174 (or 7168 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 27.

The square root of 243312309 is about 15598.4713674129. The cubic root of 243312309 is about 624.2923694635.

The spelling of 243312309 in words is "two hundred forty-three million, three hundred twelve thousand, three hundred nine".