128861820 has 96 divisors (see below), whose sum is σ = 404275200. Its totient is φ = 34074432.

The previous prime is 128861813. The next prime is 128861849. The reversal of 128861820 is 28168821.

128861820 is a `hidden beast` number, since 12 + 8 + 8 + 618 + 20 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 67641 + ... + 69519.

It is an arithmetic number, because the mean of its divisors is an integer number (4211200).

Almost surely, 2^128861820 is an apocalyptic number.

128861820 is a gapful number since it is divisible by the number (10) 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 128861820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (202137600).

128861820 is an abundant number, since it is smaller than the sum of its proper divisors (275413380).

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

128861820 is a wasteful number, since it uses less digits than its factorization.

128861820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2024 (or 2016 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 36.

The square root of 128861820 is about 11351.7320264354. The cubic root of 128861820 is about 505.0969588035.

It can be divided in two parts, 12886 and 1820, that added together give a triangular number (14706 = T₁₇₁).

The spelling of 128861820 in words is "one hundred twenty-eight million, eight hundred sixty-one thousand, eight hundred twenty".