128531520 has 168 divisors, whose sum is σ = 476240856. Its totient is φ = 31629312.

The previous prime is 128531497. The next prime is 128531551. The reversal of 128531520 is 25135821.

It is a happy number.

128531520 is a `hidden beast` number, since 128 + 531 + 5 + 2 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 207936 + 128323584 = 456^2 + 11328^2 .

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 35724 + ... + 39156.

It is an arithmetic number, because the mean of its divisors is an integer number (2834767).

Almost surely, 2^128531520 is an apocalyptic number.

128531520 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 128531520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (238120428).

128531520 is an abundant number, since it is smaller than the sum of its proper divisors (347709336).

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

128531520 is a wasteful number, since it uses less digits than its factorization.

128531520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3469 (or 3456 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 27.

The square root of 128531520 is about 11337.1742511086. The cubic root of 128531520 is about 504.6650329054.

The spelling of 128531520 in words is "one hundred twenty-eight million, five hundred thirty-one thousand, five hundred twenty".