18981329 has 2 divisors, whose sum is σ = 18981330. Its totient is φ = 18981328.

The previous prime is 18981307. The next prime is 18981343. The reversal of 18981329 is 92318981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15171025 + 3810304 = 3895^2 + 1952^2 .

It is an emirp because it is prime and its reverse (92318981) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18981329 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18981359) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9490664 + 9490665.

It is an arithmetic number, because the mean of its divisors is an integer number (9490665).

Almost surely, 2^18981329 is an apocalyptic number.

It is an amenable number.

18981329 is a deficient number, since it is larger than the sum of its proper divisors (1).

18981329 is an equidigital number, since it uses as much as digits as its factorization.

18981329 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 41.

The square root of 18981329 is about 4356.7567065421. The cubic root of 18981329 is about 266.7527296866.

It can be divided in two parts, 189 and 81329, that added together give a palindrome (81518).

The spelling of 18981329 in words is "eighteen million, nine hundred eighty-one thousand, three hundred twenty-nine".