28181511438840 has 256 divisors, whose sum is σ = 96509429251200. Its totient is φ = 7309520621568.

The previous prime is 28181511438833. The next prime is 28181511438841. The reversal of 28181511438840 is 4883411518182.

28181511438840 is a `hidden beast` number, since 2 + 8 + 1 + 8 + 1 + 511 + 4 + 3 + 88 + 40 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28181511438841) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 121242412 + ... + 121474628.

Almost surely, 2^{28181511438840} is an apocalyptic number.

28181511438840 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 28181511438840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48254714625600).

28181511438840 is an abundant number, since it is smaller than the sum of its proper divisors (68327917812360).

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

28181511438840 is a wasteful number, since it uses less digits than its factorization.

28181511438840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 235311 (or 235301 counting only the distinct ones).

The product of its (nonzero) digits is 1966080, while the sum is 54.

The spelling of 28181511438840 in words is "twenty-eight trillion, one hundred eighty-one billion, five hundred eleven million, four hundred thirty-eight thousand, eight hundred forty".