28278769 has 4 divisors (see below), whose sum is σ = 29942244. Its totient is φ = 26615296.

The previous prime is 28278763. The next prime is 28278773. The reversal of 28278769 is 96787282.

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

It can be written as a sum of positive squares in 2 ways, for example, as 26132544 + 2146225 = 5112^2 + 1465^2 .

It is a cyclic number.

It is not a de Polignac number, because 28278769 - 2¹⁹ = 27754481 is a prime.

It is a super-2 number, since 2×28278769² = 1599377552310722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28278763) 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, 831712 + ... + 831745.

It is an arithmetic number, because the mean of its divisors is an integer number (7485561).

Almost surely, 2^28278769 is an apocalyptic number.

It is an amenable number.

28278769 is a deficient number, since it is larger than the sum of its proper divisors (1663475).

28278769 is a wasteful number, since it uses less digits than its factorization.

28278769 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1663474.

The product of its digits is 677376, while the sum is 49.

The square root of 28278769 is about 5317.7785775641. The cubic root of 28278769 is about 304.6633174531.

The spelling of 28278769 in words is "twenty-eight million, two hundred seventy-eight thousand, seven hundred sixty-nine".