18489351681 has 24 divisors (see below), whose sum is σ = 27981544864. Its totient is φ = 12199144320.

The previous prime is 18489351637. The next prime is 18489351697. The reversal of 18489351681 is 18615398481.

It is a happy number.

18489351681 is a `hidden beast` number, since 1 + 8 + 48 + 9 + 3 + 516 + 81 = 666.

It is not a de Polignac number, because 18489351681 - 2⁷ = 18489351553 is a prime.

It is a super-2 number, since 2×18489351681² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18489353681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 368635 + ... + 415776.

Almost surely, 2^18489351681 is an apocalyptic number.

It is an amenable number.

18489351681 is a deficient number, since it is larger than the sum of its proper divisors (9492193183).

18489351681 is an frugal number, since it uses more digits than its factorization.

18489351681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 784523 (or 784511 counting only the distinct ones).

The product of its digits is 1658880, while the sum is 54.

The spelling of 18489351681 in words is "eighteen billion, four hundred eighty-nine million, three hundred fifty-one thousand, six hundred eighty-one".