28700820 has 72 divisors (see below), whose sum is σ = 89205480. Its totient is φ = 7464960.

The previous prime is 28700813. The next prime is 28700821. The reversal of 28700820 is 2800782.

It can be written as a sum of positive squares in 4 ways, for example, as 695556 + 28005264 = 834^2 + 5292^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28700821) 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 23 ways as a sum of consecutive naturals, for example, 5436 + ... + 9324.

It is an arithmetic number, because the mean of its divisors is an integer number (1238965).

Almost surely, 2^28700820 is an apocalyptic number.

28700820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28700820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44602740).

28700820 is an abundant number, since it is smaller than the sum of its proper divisors (60504660).

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

28700820 is a wasteful number, since it uses less digits than its factorization.

28700820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3945 (or 3940 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 27.

The square root of 28700820 is about 5357.3146258177. The cubic root of 28700820 is about 306.1715045249.

The spelling of 28700820 in words is "twenty-eight million, seven hundred thousand, eight hundred twenty".