28307840 has 64 divisors (see below), whose sum is σ = 73843920. Its totient is φ = 10291200.

The previous prime is 28307837. The next prime is 28307879. The reversal of 28307840 is 4870382.

It is a tau number, because it is divible by the number of its divisors (64).

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a junction number, because it is equal to n+sod(n) for n = 28307797 and 28307806.

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, 5030 + ... + 9050.

Almost surely, 2^28307840 is an apocalyptic number.

28307840 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 28307840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36921960).

28307840 is an abundant number, since it is smaller than the sum of its proper divisors (45536080).

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

28307840 is a wasteful number, since it uses less digits than its factorization.

28307840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4051 (or 4039 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 32.

The square root of 28307840 is about 5320.5112536297. The cubic root of 28307840 is about 304.7676811901.

The spelling of 28307840 in words is "twenty-eight million, three hundred seven thousand, eight hundred forty".