28078217 has 4 divisors (see below), whose sum is σ = 28250640. Its totient is φ = 27905796.

The previous prime is 28078189. The next prime is 28078229. The reversal of 28078217 is 71287082.

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 28078217 - 2⁸ = 28077961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28078717) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 85967 + ... + 86292.

It is an arithmetic number, because the mean of its divisors is an integer number (7062660).

Almost surely, 2^28078217 is an apocalyptic number.

It is an amenable number.

28078217 is a deficient number, since it is larger than the sum of its proper divisors (172423).

28078217 is a wasteful number, since it uses less digits than its factorization.

28078217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 172422.

The product of its (nonzero) digits is 12544, while the sum is 35.

The square root of 28078217 is about 5298.8882796300. Note that the first 3 decimals coincide. The cubic root of 28078217 is about 303.9413877363.

The spelling of 28078217 in words is "twenty-eight million, seventy-eight thousand, two hundred seventeen".