78638715 has 16 divisors (see below), whose sum is σ = 139802400. Its totient is φ = 41940576.

The previous prime is 78638689. The next prime is 78638717. The reversal of 78638715 is 51783687.

78638715 is a `hidden beast` number, since 7 + 8 + 638 + 7 + 1 + 5 = 666.

It is not a de Polignac number, because 78638715 - 2¹¹ = 78636667 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (78638717) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 291120 + ... + 291389.

It is an arithmetic number, because the mean of its divisors is an integer number (8737650).

Almost surely, 2^78638715 is an apocalyptic number.

78638715 is a deficient number, since it is larger than the sum of its proper divisors (61163685).

78638715 is a wasteful number, since it uses less digits than its factorization.

78638715 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 582523 (or 582517 counting only the distinct ones).

The product of its digits is 282240, while the sum is 45.

The square root of 78638715 is about 8867.8472584952. The cubic root of 78638715 is about 428.4289433481.

The spelling of 78638715 in words is "seventy-eight million, six hundred thirty-eight thousand, seven hundred fifteen".