28779709 has 6 divisors (see below), whose sum is σ = 33478494. Its totient is φ = 24668280.

The previous prime is 28779697. The next prime is 28779713. The reversal of 28779709 is 90797782.

It can be written as a sum of positive squares in only one way, i.e., 28676025 + 103684 = 5355^2 + 322^2 .

It is not a de Polignac number, because 28779709 - 2⁵ = 28779677 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (49), and also a Moran number because the ratio is a prime number: 587341 = 28779709 / (2 + 8 + 7 + 7 + 9 + 7 + 0 + 9).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28779719) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 293622 + ... + 293719.

It is an arithmetic number, because the mean of its divisors is an integer number (5579749).

Almost surely, 2^28779709 is an apocalyptic number.

It is an amenable number.

28779709 is a deficient number, since it is larger than the sum of its proper divisors (4698785).

28779709 is an equidigital number, since it uses as much as digits as its factorization.

28779709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 587355 (or 587348 counting only the distinct ones).

The product of its (nonzero) digits is 444528, while the sum is 49.

The square root of 28779709 is about 5364.6723105890. The cubic root of 28779709 is about 306.4517690785.

The spelling of 28779709 in words is "twenty-eight million, seven hundred seventy-nine thousand, seven hundred nine".