217105081 has 2 divisors, whose sum is σ = 217105082. Its totient is φ = 217105080.

The previous prime is 217105051. The next prime is 217105093. The reversal of 217105081 is 180501712.

217105081 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 211440681 + 5664400 = 14541^2 + 2380^2 .

It is a cyclic number.

It is not a de Polignac number, because 217105081 - 2²¹ = 215007929 is a prime.

It is a super-2 number, since 2×217105081² = 94269232392033122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (217105051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108552540 + 108552541.

It is an arithmetic number, because the mean of its divisors is an integer number (108552541).

Almost surely, 2^217105081 is an apocalyptic number.

It is an amenable number.

217105081 is a deficient number, since it is larger than the sum of its proper divisors (1).

217105081 is an equidigital number, since it uses as much as digits as its factorization.

217105081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 560, while the sum is 25.

The square root of 217105081 is about 14734.4861125185. The cubic root of 217105081 is about 601.0214831150.

Adding to 217105081 its reverse (180501712), we get a palindrome (397606793).

The spelling of 217105081 in words is "two hundred seventeen million, one hundred five thousand, eighty-one".