128921220 has 144 divisors (see below), whose sum is σ = 416078208. Its totient is φ = 33488640.

The previous prime is 128921203. The next prime is 128921227. The reversal of 128921220 is 22129821.

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

It is not an unprimeable number, because it can be changed into a prime (128921227) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 198937 + ... + 199583.

It is an arithmetic number, because the mean of its divisors is an integer number (2889432).

Almost surely, 2^128921220 is an apocalyptic number.

128921220 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 128921220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (208039104).

128921220 is an abundant number, since it is smaller than the sum of its proper divisors (287156988).

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

128921220 is a wasteful number, since it uses less digits than its factorization.

128921220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 712 (or 698 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 128921220 is about 11354.3480658292. The cubic root of 128921220 is about 505.1745565241.

The spelling of 128921220 in words is "one hundred twenty-eight million, nine hundred twenty-one thousand, two hundred twenty".