78087917 has 2 divisors, whose sum is σ = 78087918. Its totient is φ = 78087916.

The previous prime is 78087899. The next prime is 78087931. The reversal of 78087917 is 71978087.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 53743561 + 24344356 = 7331^2 + 4934^2 .

It is a cyclic number.

It is not a de Polignac number, because 78087917 - 2⁸ = 78087661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78087937) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39043958 + 39043959.

It is an arithmetic number, because the mean of its divisors is an integer number (39043959).

Almost surely, 2^78087917 is an apocalyptic number.

It is an amenable number.

78087917 is a deficient number, since it is larger than the sum of its proper divisors (1).

78087917 is an equidigital number, since it uses as much as digits as its factorization.

78087917 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 197568, while the sum is 47.

The square root of 78087917 is about 8836.7367845829. The cubic root of 78087917 is about 427.4263375240.

The spelling of 78087917 in words is "seventy-eight million, eighty-seven thousand, nine hundred seventeen".