18947 has 2 divisors, whose sum is σ = 18948. Its totient is φ = 18946.

The previous prime is 18919. The next prime is 18959. The reversal of 18947 is 74981.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 18947 - 2⁸ = 18691 is a prime.

It is a Chen prime.

It is an alternating number because its digits alternate between odd and even.

It is not a weakly prime, because it can be changed into another prime (18917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9473 + 9474.

It is an arithmetic number, because the mean of its divisors is an integer number (9474).

2¹⁸⁹⁴⁷ is an apocalyptic number.

18947 is a deficient number, since it is larger than the sum of its proper divisors (1).

18947 is an equidigital number, since it uses as much as digits as its factorization.

18947 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2016, while the sum is 29.

The square root of 18947 is about 137.6481020574. The cubic root of 18947 is about 26.6591819272.

The spelling of 18947 in words is "eighteen thousand, nine hundred forty-seven".