55128561 has 4 divisors (see below), whose sum is σ = 73504752. Its totient is φ = 36752372.

The previous prime is 55128553. The next prime is 55128581. The reversal of 55128561 is 16582155.

55128561 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 55128561 - 2³ = 55128553 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (55128511) 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, 9188091 + ... + 9188096.

It is an arithmetic number, because the mean of its divisors is an integer number (18376188).

Almost surely, 2^55128561 is an apocalyptic number.

It is an amenable number.

55128561 is a deficient number, since it is larger than the sum of its proper divisors (18376191).

55128561 is a wasteful number, since it uses less digits than its factorization.

55128561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18376190.

The product of its digits is 12000, while the sum is 33.

The square root of 55128561 is about 7424.8610088001. The cubic root of 55128561 is about 380.5913254254.

The spelling of 55128561 in words is "fifty-five million, one hundred twenty-eight thousand, five hundred sixty-one".