217121213 has 2 divisors, whose sum is σ = 217121214. Its totient is φ = 217121212.

The previous prime is 217121207. The next prime is 217121221. The reversal of 217121213 is 312121712.

217121213 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 176836804 + 40284409 = 13298^2 + 6347^2 .

It is a cyclic number.

It is not a de Polignac number, because 217121213 - 2¹⁴ = 217104829 is a prime.

It is a super-2 number, since 2×217121213² = 94283242269182738, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217121243) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108560606 + 108560607.

It is an arithmetic number, because the mean of its divisors is an integer number (108560607).

Almost surely, 2^217121213 is an apocalyptic number.

It is an amenable number.

217121213 is a deficient number, since it is larger than the sum of its proper divisors (1).

217121213 is an equidigital number, since it uses as much as digits as its factorization.

217121213 is an evil number, because the sum of its binary digits is even.

The product of its digits is 168, while the sum is 20.

The square root of 217121213 is about 14735.0335255811. The cubic root of 217121213 is about 601.0363690532.

Adding to 217121213 its reverse (312121712), we get a palindrome (529242925).

The spelling of 217121213 in words is "two hundred seventeen million, one hundred twenty-one thousand, two hundred thirteen".