217121217 has 8 divisors (see below), whose sum is σ = 297319296. Its totient is φ = 140835312.

The previous prime is 217121213. The next prime is 217121221. The reversal of 217121217 is 712121712.

It is an interprime number because it is at equal distance from previous prime (217121213) and next prime (217121221).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 217121217 - 2² = 217121213 is a prime.

It is a super-2 number, since 2×217121217² = 94283245743122178, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (217121213) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 977913 + ... + 978134.

It is an arithmetic number, because the mean of its divisors is an integer number (37164912).

Almost surely, 2^217121217 is an apocalyptic number.

It is an amenable number.

217121217 is a deficient number, since it is larger than the sum of its proper divisors (80198079).

217121217 is a wasteful number, since it uses less digits than its factorization.

217121217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1956087.

The product of its digits is 392, while the sum is 24.

The square root of 217121217 is about 14735.0336613121. The cubic root of 217121217 is about 601.0363727441.

Adding to 217121217 its reverse (712121712), we get a palindrome (929242929).

The spelling of 217121217 in words is "two hundred seventeen million, one hundred twenty-one thousand, two hundred seventeen".