28781920 has 48 divisors (see below), whose sum is σ = 70353360. Its totient is φ = 11113984.

The previous prime is 28781917. The next prime is 28781933. The reversal of 28781920 is 2918782.

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 28781920.

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 7 ways as a sum of consecutive naturals, for example, 1539 + ... + 7741.

It is an arithmetic number, because the mean of its divisors is an integer number (1465695).

Almost surely, 2^28781920 is an apocalyptic number.

28781920 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 28781920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35176680).

28781920 is an abundant number, since it is smaller than the sum of its proper divisors (41571440).

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

28781920 is a wasteful number, since it uses less digits than its factorization.

28781920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6247 (or 6239 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 28781920 is about 5364.8783769998. The cubic root of 28781920 is about 306.4596165926.

The spelling of 28781920 in words is "twenty-eight million, seven hundred eighty-one thousand, nine hundred twenty".