18438689 has 2 divisors, whose sum is σ = 18438690. Its totient is φ = 18438688.

The previous prime is 18438649. The next prime is 18438697. The reversal of 18438689 is 98683481.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17472400 + 966289 = 4180^2 + 983^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18438689 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18438619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9219344 + 9219345.

It is an arithmetic number, because the mean of its divisors is an integer number (9219345).

Almost surely, 2^18438689 is an apocalyptic number.

It is an amenable number.

18438689 is a deficient number, since it is larger than the sum of its proper divisors (1).

18438689 is an equidigital number, since it uses as much as digits as its factorization.

18438689 is an evil number, because the sum of its binary digits is even.

The product of its digits is 331776, while the sum is 47.

The square root of 18438689 is about 4294.0294596102. The cubic root of 18438689 is about 264.1861300275.

The spelling of 18438689 in words is "eighteen million, four hundred thirty-eight thousand, six hundred eighty-nine".