18381329 has 2 divisors, whose sum is σ = 18381330. Its totient is φ = 18381328.

The previous prime is 18381317. The next prime is 18381343. The reversal of 18381329 is 92318381.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17833729 + 547600 = 4223^2 + 740^2 .

It is a cyclic number.

It is not a de Polignac number, because 18381329 - 2²⁰ = 17332753 is a prime.

It is not a weakly prime, because it can be changed into another prime (18381359) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9190664 + 9190665.

It is an arithmetic number, because the mean of its divisors is an integer number (9190665).

Almost surely, 2^18381329 is an apocalyptic number.

It is an amenable number.

18381329 is a deficient number, since it is larger than the sum of its proper divisors (1).

18381329 is an equidigital number, since it uses as much as digits as its factorization.

18381329 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10368, while the sum is 35.

The square root of 18381329 is about 4287.3452158649. The cubic root of 18381329 is about 263.9118976372.

The spelling of 18381329 in words is "eighteen million, three hundred eighty-one thousand, three hundred twenty-nine".