18281689 has 2 divisors, whose sum is σ = 18281690. Its totient is φ = 18281688.

The previous prime is 18281677. The next prime is 18281713. The reversal of 18281689 is 98618281.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12131289 + 6150400 = 3483^2 + 2480^2 .

It is an emirp because it is prime and its reverse (98618281) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18281689 - 2⁷ = 18281561 is a prime.

It is not a weakly prime, because it can be changed into another prime (18281089) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9140844 + 9140845.

It is an arithmetic number, because the mean of its divisors is an integer number (9140845).

Almost surely, 2^18281689 is an apocalyptic number.

It is an amenable number.

18281689 is a deficient number, since it is larger than the sum of its proper divisors (1).

18281689 is an equidigital number, since it uses as much as digits as its factorization.

18281689 is an evil number, because the sum of its binary digits is even.

The product of its digits is 55296, while the sum is 43.

The square root of 18281689 is about 4275.7091809430. The cubic root of 18281689 is about 263.4341693978.

The spelling of 18281689 in words is "eighteen million, two hundred eighty-one thousand, six hundred eighty-nine".