78815647 has 4 divisors (see below), whose sum is σ = 78880000. Its totient is φ = 78751296.

The previous prime is 78815557. The next prime is 78815713. The reversal of 78815647 is 74651887.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 74651887 = 29 ⋅2574203.

It is a cyclic number.

It is not a de Polignac number, because 78815647 - 2¹¹ = 78813599 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 78815597 and 78815606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78815147) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30303 + ... + 32800.

It is an arithmetic number, because the mean of its divisors is an integer number (19720000).

Almost surely, 2^78815647 is an apocalyptic number.

78815647 is a deficient number, since it is larger than the sum of its proper divisors (64353).

78815647 is a wasteful number, since it uses less digits than its factorization.

78815647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64352.

The product of its digits is 376320, while the sum is 46.

The square root of 78815647 is about 8877.8176935551. The cubic root of 78815647 is about 428.7500151014.

The spelling of 78815647 in words is "seventy-eight million, eight hundred fifteen thousand, six hundred forty-seven".