18787728787 has 4 divisors (see below), whose sum is σ = 18931146696. Its totient is φ = 18644310880.

The previous prime is 18787728727. The next prime is 18787728803. The reversal of 18787728787 is 78782778781.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78782778781 = 7 ⋅11254682683.

It is a cyclic number.

It is not a de Polignac number, because 18787728787 - 2¹⁵ = 18787696019 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18787728727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 71708758 + ... + 71709019.

It is an arithmetic number, because the mean of its divisors is an integer number (4732786674).

Almost surely, 2^18787728787 is an apocalyptic number.

18787728787 is a deficient number, since it is larger than the sum of its proper divisors (143417909).

18787728787 is a wasteful number, since it uses less digits than its factorization.

18787728787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143417908.

The product of its digits is 137682944, while the sum is 70.

The spelling of 18787728787 in words is "eighteen billion, seven hundred eighty-seven million, seven hundred twenty-eight thousand, seven hundred eighty-seven".