7878917866665 has 16 divisors (see below), whose sum is σ = 12675916483776. Its totient is φ = 4178873563200.

The previous prime is 7878917866663. The next prime is 7878917866679. The reversal of 7878917866665 is 5666687198787.

It is not a de Polignac number, because 7878917866665 - 2¹ = 7878917866663 is a prime.

It is not an unprimeable number, because it can be changed into a prime (7878917866663) 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, 1450995051 + ... + 1451000480.

It is an arithmetic number, because the mean of its divisors is an integer number (792244780236).

Almost surely, 2^{7878917866665} is an apocalyptic number.

It is an amenable number.

7878917866665 is a deficient number, since it is larger than the sum of its proper divisors (4796998617111).

7878917866665 is a wasteful number, since it uses less digits than its factorization.

7878917866665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2901995720.

The product of its digits is 10241925120, while the sum is 84.

The spelling of 7878917866665 in words is "seven trillion, eight hundred seventy-eight billion, nine hundred seventeen million, eight hundred sixty-six thousand, six hundred sixty-five".