215681317 has 2 divisors, whose sum is σ = 215681318. Its totient is φ = 215681316.

The previous prime is 215681287. The next prime is 215681357. The reversal of 215681317 is 713186512.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 185804161 + 29877156 = 13631^2 + 5466^2 .

It is a cyclic number.

It is not a de Polignac number, because 215681317 - 2¹⁹ = 215157029 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (215681357) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107840658 + 107840659.

It is an arithmetic number, because the mean of its divisors is an integer number (107840659).

Almost surely, 2^215681317 is an apocalyptic number.

It is an amenable number.

215681317 is a deficient number, since it is larger than the sum of its proper divisors (1).

215681317 is an equidigital number, since it uses as much as digits as its factorization.

215681317 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10080, while the sum is 34.

The square root of 215681317 is about 14686.0926389561. The cubic root of 215681317 is about 599.7047779118.

The spelling of 215681317 in words is "two hundred fifteen million, six hundred eighty-one thousand, three hundred seventeen".