217121 has 2 divisors, whose sum is σ = 217122. Its totient is φ = 217120.

The previous prime is 217117. The next prime is 217157. The reversal of 217121 is 121712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 160000 + 57121 = 400^2 + 239^2 .

It is a cyclic number.

It is not a de Polignac number, because 217121 - 2² = 217117 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 217096 and 217105.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108560 + 108561.

It is an arithmetic number, because the mean of its divisors is an integer number (108561).

2²¹⁷¹²¹ is an apocalyptic number.

It is an amenable number.

217121 is a deficient number, since it is larger than the sum of its proper divisors (1).

217121 is an equidigital number, since it uses as much as digits as its factorization.

217121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 28, while the sum is 14.

The square root of 217121 is about 465.9624448386. The cubic root of 217121 is about 60.1036172510.

Adding to 217121 its reverse (121712), we get a palindrome (338833).

The spelling of 217121 in words is "two hundred seventeen thousand, one hundred twenty-one", and thus it is an iban number.