18656438019 has 4 divisors (see below), whose sum is σ = 24875250696. Its totient is φ = 12437625344.

The previous prime is 18656437981. The next prime is 18656438039. The reversal of 18656438019 is 91083465681.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18656438019 is a prime.

It is a super-2 number, since 2×18656438019² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (18656438039) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3109406334 + ... + 3109406339.

It is an arithmetic number, because the mean of its divisors is an integer number (6218812674).

Almost surely, 2^18656438019 is an apocalyptic number.

18656438019 is a deficient number, since it is larger than the sum of its proper divisors (6218812677).

18656438019 is an equidigital number, since it uses as much as digits as its factorization.

18656438019 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6218812676.

The product of its (nonzero) digits is 1244160, while the sum is 51.

The spelling of 18656438019 in words is "eighteen billion, six hundred fifty-six million, four hundred thirty-eight thousand, nineteen".