28520778 has 48 divisors (see below), whose sum is σ = 67408416. Its totient is φ = 7974720.

The previous prime is 28520773. The next prime is 28520809. The reversal of 28520778 is 87702582.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (28520773) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9876 + ... + 12432.

It is an arithmetic number, because the mean of its divisors is an integer number (1404342).

Almost surely, 2^28520778 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28520778, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33704208).

28520778 is an abundant number, since it is smaller than the sum of its proper divisors (38887638).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

28520778 is a wasteful number, since it uses less digits than its factorization.

28520778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2599 (or 2586 counting only the distinct ones).

The product of its (nonzero) digits is 62720, while the sum is 39.

The square root of 28520778 is about 5340.4848094532. The cubic root of 28520778 is about 305.5299502853.

The spelling of 28520778 in words is "twenty-eight million, five hundred twenty thousand, seven hundred seventy-eight".