28286640 has 120 divisors (see below), whose sum is σ = 100627488. Its totient is φ = 7096320.

The previous prime is 28286633. The next prime is 28286641. The reversal of 28286640 is 4668282.

28286640 is a `hidden beast` number, since 2 + 8 + 2 + 8 + 6 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (120).

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 = 28286595 and 28286604.

It is not an unprimeable number, because it can be changed into a prime (28286641) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11085 + ... + 13395.

Almost surely, 2^28286640 is an apocalyptic number.

28286640 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 28286640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (50313744).

28286640 is an abundant number, since it is smaller than the sum of its proper divisors (72340848).

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

28286640 is a wasteful number, since it uses less digits than its factorization.

28286640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2347 (or 2338 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 36.

The square root of 28286640 is about 5318.5185907356. The cubic root of 28286640 is about 304.6915810893.

The spelling of 28286640 in words is "twenty-eight million, two hundred eighty-six thousand, six hundred forty".