217015209 has 6 divisors (see below), whose sum is σ = 313466426. Its totient is φ = 144676800.

The previous prime is 217015193. The next prime is 217015219. The reversal of 217015209 is 902510712.

It can be written as a sum of positive squares in only one way, i.e., 140067225 + 76947984 = 11835^2 + 8772^2 .

It is not a de Polignac number, because 217015209 - 2⁴ = 217015193 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (217015219) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12056392 + ... + 12056409.

Almost surely, 2^217015209 is an apocalyptic number.

It is an amenable number.

217015209 is a deficient number, since it is larger than the sum of its proper divisors (96451217).

217015209 is a wasteful number, since it uses less digits than its factorization.

217015209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24112807 (or 24112804 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 27.

The square root of 217015209 is about 14731.4360807085. The cubic root of 217015209 is about 600.9385394739.

The spelling of 217015209 in words is "two hundred seventeen million, fifteen thousand, two hundred nine".