8181921873 has 16 divisors (see below), whose sum is σ = 11879380800. Its totient is φ = 4989337920.

The previous prime is 8181921779. The next prime is 8181921877. The reversal of 8181921873 is 3781291818.

It is a happy number.

It is not a de Polignac number, because 8181921873 - 2⁹ = 8181921361 is a prime.

It is not an unprimeable number, because it can be changed into a prime (8181921877) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2473218 + ... + 2476523.

It is an arithmetic number, because the mean of its divisors is an integer number (742461300).

Almost surely, 2^8181921873 is an apocalyptic number.

It is an amenable number.

8181921873 is a deficient number, since it is larger than the sum of its proper divisors (3697458927).

8181921873 is a wasteful number, since it uses less digits than its factorization.

8181921873 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4949792.

The product of its digits is 193536, while the sum is 48.

The square root of 8181921873 is about 90453.9765460867. The cubic root of 8181921873 is about 2015.0466710451.

The spelling of 8181921873 in words is "eight billion, one hundred eighty-one million, nine hundred twenty-one thousand, eight hundred seventy-three".