78656566 has 4 divisors (see below), whose sum is σ = 117984852. Its totient is φ = 39328282.

The previous prime is 78656563. The next prime is 78656597. The reversal of 78656566 is 66565687.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 66565687 = 5179 ⋅12853.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78656563) 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, 19664140 + ... + 19664143.

It is an arithmetic number, because the mean of its divisors is an integer number (29496213).

Almost surely, 2^78656566 is an apocalyptic number.

78656566 is a deficient number, since it is larger than the sum of its proper divisors (39328286).

78656566 is a wasteful number, since it uses less digits than its factorization.

78656566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39328285.

The product of its digits is 1814400, while the sum is 49.

The square root of 78656566 is about 8868.8537027059. The cubic root of 78656566 is about 428.4613587068.

The spelling of 78656566 in words is "seventy-eight million, six hundred fifty-six thousand, five hundred sixty-six".