28778779 has 4 divisors (see below), whose sum is σ = 28802560. Its totient is φ = 28755000.

The previous prime is 28778777. The next prime is 28778797. The reversal of 28778779 is 97787782.

It is a happy number.

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 28778779 - 2¹ = 28778777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28778777) 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 in 3 ways as a sum of consecutive naturals, for example, 9972 + ... + 12529.

It is an arithmetic number, because the mean of its divisors is an integer number (7200640).

Almost surely, 2^28778779 is an apocalyptic number.

28778779 is a deficient number, since it is larger than the sum of its proper divisors (23781).

28778779 is a wasteful number, since it uses less digits than its factorization.

28778779 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23780.

The product of its digits is 2765952, while the sum is 55.

The square root of 28778779 is about 5364.5856317147. The cubic root of 28778779 is about 306.4484681045.

The spelling of 28778779 in words is "twenty-eight million, seven hundred seventy-eight thousand, seven hundred seventy-nine".