18866389 has 2 divisors, whose sum is σ = 18866390. Its totient is φ = 18866388.

The previous prime is 18866381. The next prime is 18866399. The reversal of 18866389 is 98366881.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17497489 + 1368900 = 4183^2 + 1170^2 .

It is an emirp because it is prime and its reverse (98366881) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18866389 - 2³ = 18866381 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18866381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9433194 + 9433195.

It is an arithmetic number, because the mean of its divisors is an integer number (9433195).

Almost surely, 2^18866389 is an apocalyptic number.

It is an amenable number.

18866389 is a deficient number, since it is larger than the sum of its proper divisors (1).

18866389 is an equidigital number, since it uses as much as digits as its factorization.

18866389 is an evil number, because the sum of its binary digits is even.

The product of its digits is 497664, while the sum is 49.

The square root of 18866389 is about 4343.5456714532. The cubic root of 18866389 is about 266.2132055512.

The spelling of 18866389 in words is "eighteen million, eight hundred sixty-six thousand, three hundred eighty-nine".