28171991224728 has 384 divisors, whose sum is σ = 83912829436800. Its totient is φ = 8486500958208.

The previous prime is 28171991224711. The next prime is 28171991224759. The reversal of 28171991224728 is 82742219917182.

28171991224728 is a `hidden beast` number, since 2 + 8 + 1 + 71 + 9 + 91 + 2 + 2 + 472 + 8 = 666.

It is a super-2 number, since 2×28171991224728² (a number of 28 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 5919726813 + ... + 5919731571.

It is an arithmetic number, because the mean of its divisors is an integer number (218522993325).

Almost surely, 2^{28171991224728} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28171991224728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41956414718400).

28171991224728 is an abundant number, since it is smaller than the sum of its proper divisors (55740838212072).

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

28171991224728 is a wasteful number, since it uses less digits than its factorization.

28171991224728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5571 (or 5564 counting only the distinct ones).

The product of its digits is 16257024, while the sum is 63.

The spelling of 28171991224728 in words is "twenty-eight trillion, one hundred seventy-one billion, nine hundred ninety-one million, two hundred twenty-four thousand, seven hundred twenty-eight".