128161765 has 4 divisors (see below), whose sum is σ = 153794124. Its totient is φ = 102529408.

The previous prime is 128161757. The next prime is 128161799. The reversal of 128161765 is 567161821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 567161821 = 11353 ⋅49957.

It can be written as a sum of positive squares in 2 ways, for example, as 54081316 + 74080449 = 7354^2 + 8607^2 .

It is a cyclic number.

It is not a de Polignac number, because 128161765 - 2³ = 128161757 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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, 12816172 + ... + 12816181.

It is an arithmetic number, because the mean of its divisors is an integer number (38448531).

Almost surely, 2^128161765 is an apocalyptic number.

It is an amenable number.

128161765 is a deficient number, since it is larger than the sum of its proper divisors (25632359).

128161765 is an equidigital number, since it uses as much as digits as its factorization.

128161765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25632358.

The product of its digits is 20160, while the sum is 37.

The square root of 128161765 is about 11320.8553122103. The cubic root of 128161765 is about 504.1806338442.

The spelling of 128161765 in words is "one hundred twenty-eight million, one hundred sixty-one thousand, seven hundred sixty-five".