18516989 has 2 divisors, whose sum is σ = 18516990. Its totient is φ = 18516988.

The previous prime is 18516947. The next prime is 18516997. The reversal of 18516989 is 98961581.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18232900 + 284089 = 4270^2 + 533^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18516989 is a prime.

It is a super-2 number, since 2×18516989² = 685757763252242, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18516929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9258494 + 9258495.

It is an arithmetic number, because the mean of its divisors is an integer number (9258495).

Almost surely, 2^18516989 is an apocalyptic number.

It is an amenable number.

18516989 is a deficient number, since it is larger than the sum of its proper divisors (1).

18516989 is an equidigital number, since it uses as much as digits as its factorization.

18516989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 155520, while the sum is 47.

The square root of 18516989 is about 4303.1371114572. The cubic root of 18516989 is about 264.5595579162.

The spelling of 18516989 in words is "eighteen million, five hundred sixteen thousand, nine hundred eighty-nine".