28947220 has 36 divisors (see below), whose sum is σ = 62994204. Its totient is φ = 11173120.

The previous prime is 28947181. The next prime is 28947251. The reversal of 28947220 is 2274982.

It can be written as a sum of positive squares in 6 ways, for example, as 174724 + 28772496 = 418^2 + 5364^2 .

It is a congruent number.

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 11 ways as a sum of consecutive naturals, for example, 15960 + ... + 17680.

It is an arithmetic number, because the mean of its divisors is an integer number (1749839).

Almost surely, 2^28947220 is an apocalyptic number.

28947220 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 28947220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31497102).

28947220 is an abundant number, since it is smaller than the sum of its proper divisors (34046984).

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

28947220 is a wasteful number, since it uses less digits than its factorization.

28947220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1788 (or 1757 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 34.

The square root of 28947220 is about 5380.2620754012. The cubic root of 28947220 is about 307.0451821584.

The spelling of 28947220 in words is "twenty-eight million, nine hundred forty-seven thousand, two hundred twenty".