55128857 has 4 divisors (see below), whose sum is σ = 63004416. Its totient is φ = 47253300.

The previous prime is 55128847. The next prime is 55128859. The reversal of 55128857 is 75882155.

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 55128857 - 2²² = 50934553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (55128859) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3937769 + ... + 3937782.

It is an arithmetic number, because the mean of its divisors is an integer number (15751104).

Almost surely, 2^55128857 is an apocalyptic number.

It is an amenable number.

55128857 is a deficient number, since it is larger than the sum of its proper divisors (7875559).

55128857 is an equidigital number, since it uses as much as digits as its factorization.

55128857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7875558.

The product of its digits is 112000, while the sum is 41.

The square root of 55128857 is about 7424.8809418064. The cubic root of 55128857 is about 380.5920065897.

The spelling of 55128857 in words is "fifty-five million, one hundred twenty-eight thousand, eight hundred fifty-seven".