243281309 has 4 divisors (see below), whose sum is σ = 243313020. Its totient is φ = 243249600.

The previous prime is 243281303. The next prime is 243281317. The reversal of 243281309 is 903182342.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 903182342 = 2 ⋅451591171.

It can be written as a sum of positive squares in 2 ways, for example, as 45091225 + 198190084 = 6715^2 + 14078^2 .

It is a cyclic number.

It is not a de Polignac number, because 243281309 - 2²⁰ = 242232733 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (243281303) 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 3 ways as a sum of consecutive naturals, for example, 3659 + ... + 22359.

It is an arithmetic number, because the mean of its divisors is an integer number (60828255).

Almost surely, 2^243281309 is an apocalyptic number.

It is an amenable number.

243281309 is a deficient number, since it is larger than the sum of its proper divisors (31711).

243281309 is a wasteful number, since it uses less digits than its factorization.

243281309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31710.

The product of its (nonzero) digits is 10368, while the sum is 32.

The square root of 243281309 is about 15597.4776486456. The cubic root of 243281309 is about 624.2658550008.

The spelling of 243281309 in words is "two hundred forty-three million, two hundred eighty-one thousand, three hundred nine".