18143989 has 2 divisors, whose sum is σ = 18143990. Its totient is φ = 18143988.

The previous prime is 18143971. The next prime is 18144001. The reversal of 18143989 is 98934181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9394225 + 8749764 = 3065^2 + 2958^2 .

It is an emirp because it is prime and its reverse (98934181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18143989 - 2²¹ = 16046837 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18143929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9071994 + 9071995.

It is an arithmetic number, because the mean of its divisors is an integer number (9071995).

Almost surely, 2^18143989 is an apocalyptic number.

It is an amenable number.

18143989 is a deficient number, since it is larger than the sum of its proper divisors (1).

18143989 is an equidigital number, since it uses as much as digits as its factorization.

18143989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 62208, while the sum is 43.

The square root of 18143989 is about 4259.5761526236. The cubic root of 18143989 is about 262.7710952906.

The spelling of 18143989 in words is "eighteen million, one hundred forty-three thousand, nine hundred eighty-nine".