28409220 has 108 divisors (see below), whose sum is σ = 100275084. Its totient is φ = 6491520.

The previous prime is 28409207. The next prime is 28409221. The reversal of 28409220 is 2290482.

It can be written as a sum of positive squares in 2 ways, for example, as 16257024 + 12152196 = 4032^2 + 3486^2 .

It is not an unprimeable number, because it can be changed into a prime (28409221) 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 35 ways as a sum of consecutive naturals, for example, 7210 + ... + 10430.

It is an arithmetic number, because the mean of its divisors is an integer number (928473).

Almost surely, 2^28409220 is an apocalyptic number.

28409220 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 28409220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (50137542).

28409220 is an abundant number, since it is smaller than the sum of its proper divisors (71865864).

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

28409220 is a wasteful number, since it uses less digits than its factorization.

28409220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3250 (or 3238 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 28409220 is about 5330.0300186772. The cubic root of 28409220 is about 305.1310732880.

The spelling of 28409220 in words is "twenty-eight million, four hundred nine thousand, two hundred twenty".