28981440 has 168 divisors, whose sum is σ = 103418640. Its totient is φ = 7440384.

The previous prime is 28981439. The next prime is 28981457. The reversal of 28981440 is 4418982.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 28981395 and 28981404.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 83347 + ... + 83693.

Almost surely, 2^28981440 is an apocalyptic number.

28981440 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 28981440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (51709320).

28981440 is an abundant number, since it is smaller than the sum of its proper divisors (74437200).

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

28981440 is a wasteful number, since it uses less digits than its factorization.

28981440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 399 (or 386 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 36.

The square root of 28981440 is about 5383.4412785875. The cubic root of 28981440 is about 307.1661258222.

The spelling of 28981440 in words is "twenty-eight million, nine hundred eighty-one thousand, four hundred forty".