78523915 has 4 divisors (see below), whose sum is σ = 94228704. Its totient is φ = 62819128.

The previous prime is 78523883. The next prime is 78523919. The reversal of 78523915 is 51932587.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 51932587 = 7 ⋅7418941.

It is a cyclic number.

It is not a de Polignac number, because 78523915 - 2⁵ = 78523883 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78523919) 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, 7852387 + ... + 7852396.

It is an arithmetic number, because the mean of its divisors is an integer number (23557176).

Almost surely, 2^78523915 is an apocalyptic number.

78523915 is a deficient number, since it is larger than the sum of its proper divisors (15704789).

78523915 is a wasteful number, since it uses less digits than its factorization.

78523915 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15704788.

The product of its digits is 75600, while the sum is 40.

The square root of 78523915 is about 8861.3720720891. The cubic root of 78523915 is about 428.2203624748.

The spelling of 78523915 in words is "seventy-eight million, five hundred twenty-three thousand, nine hundred fifteen".