28781657856 has 432 divisors, whose sum is σ = 100672723200. Its totient is φ = 7945205760.

The previous prime is 28781657851. The next prime is 28781657903. The reversal of 28781657856 is 65875618782.

28781657856 is a `hidden beast` number, since 2 + 8 + 7 + 8 + 1 + 6 + 578 + 56 = 666.

It is a tau number, because it is divible by the number of its divisors (432).

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a junction number, because it is equal to n+sod(n) for n = 28781657793 and 28781657802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28781657851) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 46496715 + ... + 46497333.

Almost surely, 2^28781657856 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 28781657856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (50336361600).

28781657856 is an abundant number, since it is smaller than the sum of its proper divisors (71891065344).

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

28781657856 is an equidigital number, since it uses as much as digits as its factorization.

28781657856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 713 (or 662 counting only the distinct ones).

The product of its digits is 45158400, while the sum is 63.

The spelling of 28781657856 in words is "twenty-eight billion, seven hundred eighty-one million, six hundred fifty-seven thousand, eight hundred fifty-six".