18394982721 has 24 divisors (see below), whose sum is σ = 27510261480. Its totient is φ = 11830323456.

The previous prime is 18394982707. The next prime is 18394982813. The reversal of 18394982721 is 12728949381.

18394982721 is a `hidden beast` number, since 1 + 83 + 9 + 498 + 2 + 72 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 1081686321 + 17313296400 = 32889^2 + 131580^2 .

It is not a de Polignac number, because 18394982721 - 2¹¹ = 18394980673 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18394982521) 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, 281835 + ... + 340911.

It is an arithmetic number, because the mean of its divisors is an integer number (1146260895).

Almost surely, 2^18394982721 is an apocalyptic number.

It is an amenable number.

18394982721 is a deficient number, since it is larger than the sum of its proper divisors (9115278759).

18394982721 is a wasteful number, since it uses less digits than its factorization.

18394982721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60305 (or 60302 counting only the distinct ones).

The product of its digits is 1741824, while the sum is 54.

The spelling of 18394982721 in words is "eighteen billion, three hundred ninety-four million, nine hundred eighty-two thousand, seven hundred twenty-one".