128121840 has 240 divisors, whose sum is σ = 536679936. Its totient is φ = 26611200.

The previous prime is 128121821. The next prime is 128121869. The reversal of 128121840 is 48121821.

It is a tau number, because it is divible by the number of its divisors (240).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 54285 + ... + 56595.

Almost surely, 2^128121840 is an apocalyptic number.

128121840 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 128121840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (268339968).

128121840 is an abundant number, since it is smaller than the sum of its proper divisors (408558096).

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

128121840 is a wasteful number, since it uses less digits than its factorization.

128121840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2348 (or 2339 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 27.

The square root of 128121840 is about 11319.0918363621. The cubic root of 128121840 is about 504.1282742282.

The spelling of 128121840 in words is "one hundred twenty-eight million, one hundred twenty-one thousand, eight hundred forty".