78257717 has 2 divisors, whose sum is σ = 78257718. Its totient is φ = 78257716.

The previous prime is 78257687. The next prime is 78257719. The reversal of 78257717 is 71775287.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76983076 + 1274641 = 8774^2 + 1129^2 .

It is an emirp because it is prime and its reverse (71775287) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78257717 - 2¹⁰ = 78256693 is a prime.

It is a super-2 number, since 2×78257717² = 12248540540104178, which contains 22 as substring.

Together with 78257719, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78257719) 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, 39128858 + 39128859.

It is an arithmetic number, because the mean of its divisors is an integer number (39128859).

Almost surely, 2^78257717 is an apocalyptic number.

It is an amenable number.

78257717 is a deficient number, since it is larger than the sum of its proper divisors (1).

78257717 is an equidigital number, since it uses as much as digits as its factorization.

78257717 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 192080, while the sum is 44.

The square root of 78257717 is about 8846.3391863527. The cubic root of 78257717 is about 427.7359221256.

The spelling of 78257717 in words is "seventy-eight million, two hundred fifty-seven thousand, seven hundred seventeen".