18281309 has 2 divisors, whose sum is σ = 18281310. Its totient is φ = 18281308.

The previous prime is 18281279. The next prime is 18281353. The reversal of 18281309 is 90318281.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16630084 + 1651225 = 4078^2 + 1285^2 .

It is a cyclic number.

It is not a de Polignac number, because 18281309 - 2¹⁶ = 18215773 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18280309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9140654 + 9140655.

It is an arithmetic number, because the mean of its divisors is an integer number (9140655).

Almost surely, 2^18281309 is an apocalyptic number.

It is an amenable number.

18281309 is a deficient number, since it is larger than the sum of its proper divisors (1).

18281309 is an equidigital number, since it uses as much as digits as its factorization.

18281309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3456, while the sum is 32.

The square root of 18281309 is about 4275.6647436393. The cubic root of 18281309 is about 263.4323441530.

The spelling of 18281309 in words is "eighteen million, two hundred eighty-one thousand, three hundred nine".