217248509 has 2 divisors, whose sum is σ = 217248510. Its totient is φ = 217248508.

The previous prime is 217248503. The next prime is 217248539. The reversal of 217248509 is 905842712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 216737284 + 511225 = 14722^2 + 715^2 .

It is a cyclic number.

It is not a de Polignac number, because 217248509 - 2²⁰ = 216199933 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217248503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108624254 + 108624255.

It is an arithmetic number, because the mean of its divisors is an integer number (108624255).

Almost surely, 2^217248509 is an apocalyptic number.

It is an amenable number.

217248509 is a deficient number, since it is larger than the sum of its proper divisors (1).

217248509 is an equidigital number, since it uses as much as digits as its factorization.

217248509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40320, while the sum is 38.

The square root of 217248509 is about 14739.3523941861. The cubic root of 217248509 is about 601.1538066466.

The spelling of 217248509 in words is "two hundred seventeen million, two hundred forty-eight thousand, five hundred nine".