28501220 has 48 divisors (see below), whose sum is σ = 65657088. Its totient is φ = 10306560.

The previous prime is 28501181. The next prime is 28501237. The reversal of 28501220 is 2210582.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 28501192 and 28501201.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 77477 + ... + 77843.

It is an arithmetic number, because the mean of its divisors is an integer number (1367856).

Almost surely, 2^28501220 is an apocalyptic number.

28501220 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 28501220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32828544).

28501220 is an abundant number, since it is smaller than the sum of its proper divisors (37155868).

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

28501220 is a wasteful number, since it uses less digits than its factorization.

28501220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 740 (or 738 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 20.

The square root of 28501220 is about 5338.6533882619. The cubic root of 28501220 is about 305.4600957020.

The spelling of 28501220 in words is "twenty-eight million, five hundred one thousand, two hundred twenty".