128838640720 has 20 divisors (see below), whose sum is σ = 299549839860. Its totient is φ = 51535456256.

The previous prime is 128838640717. The next prime is 128838640727. The reversal of 128838640720 is 27046838821.

It can be written as a sum of positive squares in 2 ways, for example, as 63421370896 + 65417269824 = 251836^2 + 255768^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128838640727) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 805241425 + ... + 805241584.

It is an arithmetic number, because the mean of its divisors is an integer number (14977491993).

Almost surely, 2^128838640720 is an apocalyptic number.

128838640720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

128838640720 is an abundant number, since it is smaller than the sum of its proper divisors (170711199140).

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

128838640720 is a wasteful number, since it uses less digits than its factorization.

128838640720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1610483022 (or 1610483016 counting only the distinct ones).

The product of its (nonzero) digits is 1032192, while the sum is 49.

The spelling of 128838640720 in words is "one hundred twenty-eight billion, eight hundred thirty-eight million, six hundred forty thousand, seven hundred twenty".