28307880 has 80 divisors (see below), whose sum is σ = 95156820. Its totient is φ = 7547904.

The previous prime is 28307879. The next prime is 28307887. The reversal of 28307880 is 8870382.

It can be written as a sum of positive squares in 2 ways, for example, as 27815076 + 492804 = 5274^2 + 702^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (28307887) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 1129 + ... + 7608.

Almost surely, 2^28307880 is an apocalyptic number.

28307880 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 28307880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47578410).

28307880 is an abundant number, since it is smaller than the sum of its proper divisors (66848940).

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

28307880 is a wasteful number, since it uses less digits than its factorization.

28307880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8760 (or 8747 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 36.

The square root of 28307880 is about 5320.5150126656. The cubic root of 28307880 is about 304.7678247393.

The spelling of 28307880 in words is "twenty-eight million, three hundred seven thousand, eight hundred eighty".