18938402647 has 4 divisors (see below), whose sum is σ = 18938685616. Its totient is φ = 18938119680.

The previous prime is 18938402641. The next prime is 18938402663. The reversal of 18938402647 is 74620483981.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 18938402647 - 2¹⁹ = 18937878359 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18938402594 and 18938402603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18938402641) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 21463 + ... + 195799.

It is an arithmetic number, because the mean of its divisors is an integer number (4734671404).

Almost surely, 2^18938402647 is an apocalyptic number.

18938402647 is a deficient number, since it is larger than the sum of its proper divisors (282969).

18938402647 is a wasteful number, since it uses less digits than its factorization.

18938402647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 282968.

The product of its (nonzero) digits is 2322432, while the sum is 52.

The spelling of 18938402647 in words is "eighteen billion, nine hundred thirty-eight million, four hundred two thousand, six hundred forty-seven".