128917920 has 96 divisors (see below), whose sum is σ = 407695680. Its totient is φ = 34242560.

The previous prime is 128917903. The next prime is 128917939. The reversal of 128917920 is 29719821.

It is a tau number, because it is divible by the number of its divisors (96).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 200800 + ... + 201440.

It is an arithmetic number, because the mean of its divisors is an integer number (4246830).

Almost surely, 2^128917920 is an apocalyptic number.

128917920 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 128917920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (203847840).

128917920 is an abundant number, since it is smaller than the sum of its proper divisors (278777760).

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

128917920 is a wasteful number, since it uses less digits than its factorization.

128917920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1078 (or 1070 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 39.

The square root of 128917920 is about 11354.2027461200. The cubic root of 128917920 is about 505.1702461650.

The spelling of 128917920 in words is "one hundred twenty-eight million, nine hundred seventeen thousand, nine hundred twenty".