91278217 has 2 divisors, whose sum is σ = 91278218. Its totient is φ = 91278216.

The previous prime is 91278203. The next prime is 91278221. The reversal of 91278217 is 71287219.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 85914361 + 5363856 = 9269^2 + 2316^2 .

It is a cyclic number.

It is not a de Polignac number, because 91278217 - 2¹¹ = 91276169 is a prime.

It is not a weakly prime, because it can be changed into another prime (91278227) 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, 45639108 + 45639109.

It is an arithmetic number, because the mean of its divisors is an integer number (45639109).

Almost surely, 2^91278217 is an apocalyptic number.

It is an amenable number.

91278217 is a deficient number, since it is larger than the sum of its proper divisors (1).

91278217 is an equidigital number, since it uses as much as digits as its factorization.

91278217 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14112, while the sum is 37.

The square root of 91278217 is about 9553.9634183934. The cubic root of 91278217 is about 450.2520678312.

The spelling of 91278217 in words is "ninety-one million, two hundred seventy-eight thousand, two hundred seventeen".