8686640978 has 4 divisors (see below), whose sum is σ = 13029961470. Its totient is φ = 4343320488.

The previous prime is 8686640971. The next prime is 8686641017. The reversal of 8686640978 is 8790466868.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 8529815449 + 156825529 = 92357^2 + 12523^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 8686640978.

It is not an unprimeable number, because it can be changed into a prime (8686640971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2171660243 + ... + 2171660246.

Almost surely, 2^8686640978 is an apocalyptic number.

8686640978 is a deficient number, since it is larger than the sum of its proper divisors (4343320492).

8686640978 is a wasteful number, since it uses less digits than its factorization.

8686640978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4343320491.

The product of its (nonzero) digits is 27869184, while the sum is 62.

The square root of 8686640978 is about 93202.1511447027. The cubic root of 8686640978 is about 2055.6568705804.

The spelling of 8686640978 in words is "eight billion, six hundred eighty-six million, six hundred forty thousand, nine hundred seventy-eight".