28028857 has 4 divisors (see below), whose sum is σ = 29504080. Its totient is φ = 26553636.

The previous prime is 28028839. The next prime is 28028863. The reversal of 28028857 is 75882082.

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, and also an emirpimes, since its reverse is a distinct semiprime: 75882082 = 2 ⋅37941041.

It is a cyclic number.

It is not a de Polignac number, because 28028857 - 2⁷ = 28028729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28028807) by changing a digit.

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, 737583 + ... + 737620.

It is an arithmetic number, because the mean of its divisors is an integer number (7376020).

Almost surely, 2^28028857 is an apocalyptic number.

It is an amenable number.

28028857 is a deficient number, since it is larger than the sum of its proper divisors (1475223).

28028857 is a wasteful number, since it uses less digits than its factorization.

28028857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1475222.

The product of its (nonzero) digits is 71680, while the sum is 40.

The square root of 28028857 is about 5294.2286501435. The cubic root of 28028857 is about 303.7631790474.

The spelling of 28028857 in words is "twenty-eight million, twenty-eight thousand, eight hundred fifty-seven".