78665791 has 8 divisors (see below), whose sum is σ = 80753024. Its totient is φ = 76590360.

The previous prime is 78665779. The next prime is 78665801. The reversal of 78665791 is 19756687.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 78665791 - 2²³ = 70277183 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78665701) 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 in 7 ways as a sum of consecutive naturals, for example, 11470 + ... + 16996.

It is an arithmetic number, because the mean of its divisors is an integer number (10094128).

Almost surely, 2^78665791 is an apocalyptic number.

78665791 is a deficient number, since it is larger than the sum of its proper divisors (2087233).

78665791 is a wasteful number, since it uses less digits than its factorization.

78665791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5901.

The product of its digits is 635040, while the sum is 49.

The square root of 78665791 is about 8869.3737659431. The cubic root of 78665791 is about 428.4781083215.

The spelling of 78665791 in words is "seventy-eight million, six hundred sixty-five thousand, seven hundred ninety-one".