78455665 has 4 divisors (see below), whose sum is σ = 94146804. Its totient is φ = 62764528.

The previous prime is 78455633. The next prime is 78455669. The reversal of 78455665 is 56655487.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56655487 = 7 ⋅8093641.

It can be written as a sum of positive squares in 2 ways, for example, as 29062881 + 49392784 = 5391^2 + 7028^2 .

It is a cyclic number.

It is not a de Polignac number, because 78455665 - 2⁵ = 78455633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78455669) 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 3 ways as a sum of consecutive naturals, for example, 7845562 + ... + 7845571.

It is an arithmetic number, because the mean of its divisors is an integer number (23536701).

Almost surely, 2^78455665 is an apocalyptic number.

It is an amenable number.

78455665 is a deficient number, since it is larger than the sum of its proper divisors (15691139).

78455665 is a wasteful number, since it uses less digits than its factorization.

78455665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15691138.

The product of its digits is 1008000, while the sum is 46.

The square root of 78455665 is about 8857.5202511764. The cubic root of 78455665 is about 428.0962622300.

The spelling of 78455665 in words is "seventy-eight million, four hundred fifty-five thousand, six hundred sixty-five".