18973217 has 2 divisors, whose sum is σ = 18973218. Its totient is φ = 18973216.

The previous prime is 18973189. The next prime is 18973223. The reversal of 18973217 is 71237981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10394176 + 8579041 = 3224^2 + 2929^2 .

It is an emirp because it is prime and its reverse (71237981) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18973217 - 2¹⁰ = 18972193 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18973237) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9486608 + 9486609.

It is an arithmetic number, because the mean of its divisors is an integer number (9486609).

Almost surely, 2^18973217 is an apocalyptic number.

It is an amenable number.

18973217 is a deficient number, since it is larger than the sum of its proper divisors (1).

18973217 is an equidigital number, since it uses as much as digits as its factorization.

18973217 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21168, while the sum is 38.

The square root of 18973217 is about 4355.8256393019. The cubic root of 18973217 is about 266.7147238042.

The spelling of 18973217 in words is "eighteen million, nine hundred seventy-three thousand, two hundred seventeen".