28778920 has 48 divisors (see below), whose sum is σ = 68374260. Its totient is φ = 10900224.

The previous prime is 28778891. The next prime is 28778941. The reversal of 28778920 is 2987782.

It can be written as a sum of positive squares in 2 ways, for example, as 28708164 + 70756 = 5358^2 + 266^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13444 + ... + 15436.

Almost surely, 2^28778920 is an apocalyptic number.

28778920 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 28778920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34187130).

28778920 is an abundant number, since it is smaller than the sum of its proper divisors (39595340).

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

28778920 is a wasteful number, since it uses less digits than its factorization.

28778920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2042 (or 2019 counting only the distinct ones).

The product of its (nonzero) digits is 112896, while the sum is 43.

The square root of 28778920 is about 5364.5987734406. The cubic root of 28778920 is about 306.4489685793.

The spelling of 28778920 in words is "twenty-eight million, seven hundred seventy-eight thousand, nine hundred twenty".