128321550 has 192 divisors, whose sum is σ = 416163840. Its totient is φ = 28460160.

The previous prime is 128321509. The next prime is 128321551. The reversal of 128321550 is 55123821.

It is a happy number.

128321550 is a `hidden beast` number, since 12 + 83 + 21 + 550 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128321551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 349467 + ... + 349833.

It is an arithmetic number, because the mean of its divisors is an integer number (2167520).

Almost surely, 2^128321550 is an apocalyptic number.

128321550 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 128321550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (208081920).

128321550 is an abundant number, since it is smaller than the sum of its proper divisors (287842290).

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

128321550 is a wasteful number, since it uses less digits than its factorization.

128321550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 432 (or 421 counting only the distinct ones).

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

The square root of 128321550 is about 11327.9102221019. The cubic root of 128321550 is about 504.3900750044.

The spelling of 128321550 in words is "one hundred twenty-eight million, three hundred twenty-one thousand, five hundred fifty".