18661289 has 2 divisors, whose sum is σ = 18661290. Its totient is φ = 18661288.

The previous prime is 18661277. The next prime is 18661327. The reversal of 18661289 is 98216681.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11505664 + 7155625 = 3392^2 + 2675^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18661289 is a prime.

It is not a weakly prime, because it can be changed into another prime (18661259) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9330644 + 9330645.

It is an arithmetic number, because the mean of its divisors is an integer number (9330645).

Almost surely, 2^18661289 is an apocalyptic number.

It is an amenable number.

18661289 is a deficient number, since it is larger than the sum of its proper divisors (1).

18661289 is an equidigital number, since it uses as much as digits as its factorization.

18661289 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 41472, while the sum is 41.

The square root of 18661289 is about 4319.8714101232. The cubic root of 18661289 is about 265.2450042187.

The spelling of 18661289 in words is "eighteen million, six hundred sixty-one thousand, two hundred eighty-nine".