28778526809 has 4 divisors (see below), whose sum is σ = 29063462820. Its totient is φ = 28493590800.

The previous prime is 28778526793. The next prime is 28778526827. The reversal of 28778526809 is 90862587782.

It is a happy number.

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 25028189209 + 3750337600 = 158203^2 + 61240^2 .

It is a cyclic number.

It is not a de Polignac number, because 28778526809 - 2⁴ = 28778526793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28778526899) 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, 142467854 + ... + 142468055.

It is an arithmetic number, because the mean of its divisors is an integer number (7265865705).

Almost surely, 2^28778526809 is an apocalyptic number.

It is an amenable number.

28778526809 is a deficient number, since it is larger than the sum of its proper divisors (284936011).

28778526809 is a wasteful number, since it uses less digits than its factorization.

28778526809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 284936010.

The product of its (nonzero) digits is 27095040, while the sum is 62.

The spelling of 28778526809 in words is "twenty-eight billion, seven hundred seventy-eight million, five hundred twenty-six thousand, eight hundred nine".