78665771 has 2 divisors, whose sum is σ = 78665772. Its totient is φ = 78665770.

The previous prime is 78665753. The next prime is 78665779. The reversal of 78665771 is 17756687.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 78665771 - 2⁶ = 78665707 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (78665779) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39332885 + 39332886.

It is an arithmetic number, because the mean of its divisors is an integer number (39332886).

Almost surely, 2^78665771 is an apocalyptic number.

78665771 is a deficient number, since it is larger than the sum of its proper divisors (1).

78665771 is an equidigital number, since it uses as much as digits as its factorization.

78665771 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 493920, while the sum is 47.

The square root of 78665771 is about 8869.3726384677. The cubic root of 78665771 is about 428.4780720093.

The spelling of 78665771 in words is "seventy-eight million, six hundred sixty-five thousand, seven hundred seventy-one".