16778128405 has 4 divisors (see below), whose sum is σ = 20133754092. Its totient is φ = 13422502720.

The previous prime is 16778128403. The next prime is 16778128421. The reversal of 16778128405 is 50482187761.

16778128405 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50482187761 = 37 ⋅1364383453.

It can be written as a sum of positive squares in 2 ways, for example, as 3174871716 + 13603256689 = 56346^2 + 116633^2 .

It is not a de Polignac number, because 16778128405 - 2¹ = 16778128403 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16778128403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1677812836 + ... + 1677812845.

It is an arithmetic number, because the mean of its divisors is an integer number (5033438523).

Almost surely, 2^16778128405 is an apocalyptic number.

It is an amenable number.

16778128405 is a deficient number, since it is larger than the sum of its proper divisors (3355625687).

16778128405 is an equidigital number, since it uses as much as digits as its factorization.

16778128405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3355625686.

The product of its (nonzero) digits is 752640, while the sum is 49.

The spelling of 16778128405 in words is "sixteen billion, seven hundred seventy-eight million, one hundred twenty-eight thousand, four hundred five".