18748661 has 2 divisors, whose sum is σ = 18748662. Its totient is φ = 18748660.

The previous prime is 18748643. The next prime is 18748673. The reversal of 18748661 is 16684781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18541636 + 207025 = 4306^2 + 455^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18748661 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18748361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9374330 + 9374331.

It is an arithmetic number, because the mean of its divisors is an integer number (9374331).

Almost surely, 2^18748661 is an apocalyptic number.

It is an amenable number.

18748661 is a deficient number, since it is larger than the sum of its proper divisors (1).

18748661 is an equidigital number, since it uses as much as digits as its factorization.

18748661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 64512, while the sum is 41.

The square root of 18748661 is about 4329.9724017596. The cubic root of 18748661 is about 265.6583181459.

The spelling of 18748661 in words is "eighteen million, seven hundred forty-eight thousand, six hundred sixty-one".