18668549 has 2 divisors, whose sum is σ = 18668550. Its totient is φ = 18668548.

The previous prime is 18668513. The next prime is 18668557. The reversal of 18668549 is 94586681.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16728100 + 1940449 = 4090^2 + 1393^2 .

It is a cyclic number.

It is not a de Polignac number, because 18668549 - 2²⁴ = 1891333 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18668599) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9334274 + 9334275.

It is an arithmetic number, because the mean of its divisors is an integer number (9334275).

Almost surely, 2^18668549 is an apocalyptic number.

It is an amenable number.

18668549 is a deficient number, since it is larger than the sum of its proper divisors (1).

18668549 is an equidigital number, since it uses as much as digits as its factorization.

18668549 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 414720, while the sum is 47.

The square root of 18668549 is about 4320.7116312015. The cubic root of 18668549 is about 265.2793967887.

The spelling of 18668549 in words is "eighteen million, six hundred sixty-eight thousand, five hundred forty-nine".