128021819161 has 4 divisors (see below), whose sum is σ = 128025044532. Its totient is φ = 128018593792.

The previous prime is 128021819153. The next prime is 128021819209. The reversal of 128021819161 is 161918120821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 161918120821 = 19 ⋅8522006359.

It can be written as a sum of positive squares in 2 ways, for example, as 68084986761 + 59936832400 = 260931^2 + 244820^2 .

It is a cyclic number.

It is not a de Polignac number, because 128021819161 - 2³ = 128021819153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128021819141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1552396 + ... + 1632781.

It is an arithmetic number, because the mean of its divisors is an integer number (32006261133).

Almost surely, 2^128021819161 is an apocalyptic number.

It is an amenable number.

128021819161 is a deficient number, since it is larger than the sum of its proper divisors (3225371).

128021819161 is an equidigital number, since it uses as much as digits as its factorization.

128021819161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3225370.

The product of its (nonzero) digits is 13824, while the sum is 40.

Adding to 128021819161 its reverse (161918120821), we get a palindrome (289939939982).

The spelling of 128021819161 in words is "one hundred twenty-eight billion, twenty-one million, eight hundred nineteen thousand, one hundred sixty-one".