16128538081 has 4 divisors (see below), whose sum is σ = 16309757700. Its totient is φ = 15947318464.

The previous prime is 16128538079. The next prime is 16128538087. The reversal of 16128538081 is 18083582161.

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

It can be written as a sum of positive squares in 2 ways, for example, as 5314410000 + 10814128081 = 72900^2 + 103991^2 .

It is a cyclic number.

It is not a de Polignac number, because 16128538081 - 2¹ = 16128538079 is a prime.

It is a super-2 number, since 2×16128538081² (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 (16128538087) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 90609676 + ... + 90609853.

It is an arithmetic number, because the mean of its divisors is an integer number (4077439425).

Almost surely, 2^16128538081 is an apocalyptic number.

It is an amenable number.

16128538081 is a deficient number, since it is larger than the sum of its proper divisors (181219619).

16128538081 is an equidigital number, since it uses as much as digits as its factorization.

16128538081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 181219618.

The product of its (nonzero) digits is 92160, while the sum is 43.

The spelling of 16128538081 in words is "sixteen billion, one hundred twenty-eight million, five hundred thirty-eight thousand, eighty-one".