12181721278 has 4 divisors (see below), whose sum is σ = 18272581920. Its totient is φ = 6090860638.

The previous prime is 12181721261. The next prime is 12181721291. The reversal of 12181721278 is 87212718121.

12181721278 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a self number, because there is not a number n which added to its sum of digits gives 12181721278.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3045430318 + ... + 3045430321.

It is an arithmetic number, because the mean of its divisors is an integer number (4568145480).

Almost surely, 2^12181721278 is an apocalyptic number.

12181721278 is a deficient number, since it is larger than the sum of its proper divisors (6090860642).

12181721278 is an equidigital number, since it uses as much as digits as its factorization.

12181721278 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6090860641.

The product of its digits is 25088, while the sum is 40.

The spelling of 12181721278 in words is "twelve billion, one hundred eighty-one million, seven hundred twenty-one thousand, two hundred seventy-eight".