18189947 has 2 divisors, whose sum is σ = 18189948. Its totient is φ = 18189946.

The previous prime is 18189929. The next prime is 18189961. The reversal of 18189947 is 74998181.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 18189947 - 2⁶ = 18189883 is a prime.

It is not a weakly prime, because it can be changed into another prime (18189917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9094973 + 9094974.

It is an arithmetic number, because the mean of its divisors is an integer number (9094974).

Almost surely, 2^18189947 is an apocalyptic number.

18189947 is a deficient number, since it is larger than the sum of its proper divisors (1).

18189947 is an equidigital number, since it uses as much as digits as its factorization.

18189947 is an evil number, because the sum of its binary digits is even.

The product of its digits is 145152, while the sum is 47.

The square root of 18189947 is about 4264.9674090197. The cubic root of 18189947 is about 262.9927711295.

The spelling of 18189947 in words is "eighteen million, one hundred eighty-nine thousand, nine hundred forty-seven".