28278491 has 4 divisors (see below), whose sum is σ = 28301592. Its totient is φ = 28255392.

The previous prime is 28278487. The next prime is 28278493. The reversal of 28278491 is 19487282.

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 28278491 - 2² = 28278487 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28278493) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9605 + ... + 12198.

It is an arithmetic number, because the mean of its divisors is an integer number (7075398).

Almost surely, 2^28278491 is an apocalyptic number.

28278491 is a deficient number, since it is larger than the sum of its proper divisors (23101).

28278491 is a wasteful number, since it uses less digits than its factorization.

28278491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23100.

The product of its digits is 64512, while the sum is 41.

The square root of 28278491 is about 5317.7524387658. The cubic root of 28278491 is about 304.6623190989.

The spelling of 28278491 in words is "twenty-eight million, two hundred seventy-eight thousand, four hundred ninety-one".