78857815 has 16 divisors (see below), whose sum is σ = 103654080. Its totient is φ = 57326080.

The previous prime is 78857813. The next prime is 78857819. The reversal of 78857815 is 51875887.

It is not a de Polignac number, because 78857815 - 2¹ = 78857813 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78857813) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13531 + ... + 18460.

It is an arithmetic number, because the mean of its divisors is an integer number (6478380).

Almost surely, 2^78857815 is an apocalyptic number.

78857815 is a deficient number, since it is larger than the sum of its proper divisors (24796265).

78857815 is a wasteful number, since it uses less digits than its factorization.

78857815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32042.

The product of its digits is 627200, while the sum is 49.

The square root of 78857815 is about 8880.1922839542. The cubic root of 78857815 is about 428.8264648419.

The spelling of 78857815 in words is "seventy-eight million, eight hundred fifty-seven thousand, eight hundred fifteen".