65128561 has 4 divisors (see below), whose sum is σ = 68556400. Its totient is φ = 61700724.

The previous prime is 65128549. The next prime is 65128579. The reversal of 65128561 is 16582156.

It is a happy number.

65128561 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 a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 65128561 - 2⁵ = 65128529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (65128501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1713891 + ... + 1713928.

It is an arithmetic number, because the mean of its divisors is an integer number (17139100).

Almost surely, 2^65128561 is an apocalyptic number.

It is an amenable number.

65128561 is a deficient number, since it is larger than the sum of its proper divisors (3427839).

65128561 is a wasteful number, since it uses less digits than its factorization.

65128561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3427838.

The product of its digits is 14400, while the sum is 34.

The square root of 65128561 is about 8070.2268245694. The cubic root of 65128561 is about 402.3374825805.

The spelling of 65128561 in words is "sixty-five million, one hundred twenty-eight thousand, five hundred sixty-one".