28396778 has 4 divisors (see below), whose sum is σ = 42595170. Its totient is φ = 14198388.

The previous prime is 28396777. The next prime is 28396799. The reversal of 28396778 is 87769382.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 87769382 = 2 ⋅43884691.

It can be written as a sum of positive squares in only one way, i.e., 14876449 + 13520329 = 3857^2 + 3677^2 .

It is not an unprimeable number, because it can be changed into a prime (28396777) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7099193 + ... + 7099196.

Almost surely, 2^28396778 is an apocalyptic number.

28396778 is a deficient number, since it is larger than the sum of its proper divisors (14198392).

28396778 is a wasteful number, since it uses less digits than its factorization.

28396778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14198391.

The product of its digits is 1016064, while the sum is 50.

The square root of 28396778 is about 5328.8627304520. The cubic root of 28396778 is about 305.0865220804.

The spelling of 28396778 in words is "twenty-eight million, three hundred ninety-six thousand, seven hundred seventy-eight".