128720856 has 64 divisors (see below), whose sum is σ = 353491200. Its totient is φ = 38736000.

The previous prime is 128720849. The next prime is 128720861. The reversal of 128720856 is 658027821.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38250 + ... + 41478.

It is an arithmetic number, because the mean of its divisors is an integer number (5523300).

Almost surely, 2^128720856 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 128720856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (176745600).

128720856 is an abundant number, since it is smaller than the sum of its proper divisors (224770344).

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

128720856 is a wasteful number, since it uses less digits than its factorization.

128720856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3400 (or 3396 counting only the distinct ones).

The product of its (nonzero) digits is 53760, while the sum is 39.

The square root of 128720856 is about 11345.5214071456. The cubic root of 128720856 is about 504.9127137314.

The spelling of 128720856 in words is "one hundred twenty-eight million, seven hundred twenty thousand, eight hundred fifty-six".