8181911978 has 8 divisors (see below), whose sum is σ = 12440989668. Its totient is φ = 4034915424.

The previous prime is 8181911921. The next prime is 8181912001. The reversal of 8181911978 is 8791191818.

8181911978 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 7703046289 + 478865689 = 87767^2 + 21883^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28020101 + ... + 28020392.

Almost surely, 2^8181911978 is an apocalyptic number.

8181911978 is a deficient number, since it is larger than the sum of its proper divisors (4259077690).

8181911978 is a wasteful number, since it uses less digits than its factorization.

8181911978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56040568.

The product of its digits is 290304, while the sum is 53.

The square root of 8181911978 is about 90453.9218497462. The cubic root of 8181911978 is about 2015.0458587301.

The spelling of 8181911978 in words is "eight billion, one hundred eighty-one million, nine hundred eleven thousand, nine hundred seventy-eight".