217242187 has 2 divisors, whose sum is σ = 217242188. Its totient is φ = 217242186.

The previous prime is 217242119. The next prime is 217242191. The reversal of 217242187 is 781242712.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-217242187 is a prime.

It is not a weakly prime, because it can be changed into another prime (217242587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108621093 + 108621094.

It is an arithmetic number, because the mean of its divisors is an integer number (108621094).

Almost surely, 2^217242187 is an apocalyptic number.

217242187 is a deficient number, since it is larger than the sum of its proper divisors (1).

217242187 is an equidigital number, since it uses as much as digits as its factorization.

217242187 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12544, while the sum is 34.

The square root of 217242187 is about 14739.1379327286. The cubic root of 217242187 is about 601.1479753351.

Adding to 217242187 its reverse (781242712), we get a palindrome (998484899).

The spelling of 217242187 in words is "two hundred seventeen million, two hundred forty-two thousand, one hundred eighty-seven".