28278647 has 4 divisors (see below), whose sum is σ = 28301376. Its totient is φ = 28255920.

The previous prime is 28278617. The next prime is 28278671. The reversal of 28278647 is 74687282.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 28278647 - 2⁶ = 28278583 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28278598 and 28278607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28278617) 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, 9383 + ... + 12024.

It is an arithmetic number, because the mean of its divisors is an integer number (7075344).

Almost surely, 2^28278647 is an apocalyptic number.

28278647 is a deficient number, since it is larger than the sum of its proper divisors (22729).

28278647 is a wasteful number, since it uses less digits than its factorization.

28278647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22728.

The product of its digits is 301056, while the sum is 44.

The square root of 28278647 is about 5317.7671065965. The cubic root of 28278647 is about 304.6628793272.

The spelling of 28278647 in words is "twenty-eight million, two hundred seventy-eight thousand, six hundred forty-seven".