129128240 has 40 divisors (see below), whose sum is σ = 304349568. Its totient is φ = 50941440.

The previous prime is 129128239. The next prime is 129128249. The reversal of 129128240 is 42821921.

It is a tau number, because it is divible by the number of its divisors (40).

It is not an unprimeable number, because it can be changed into a prime (129128249) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5216 + ... + 16895.

Almost surely, 2^129128240 is an apocalyptic number.

129128240 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

129128240 is an abundant number, since it is smaller than the sum of its proper divisors (175221328).

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

129128240 is a wasteful number, since it uses less digits than its factorization.

129128240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22197 (or 22191 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 129128240 is about 11363.4607404611. The cubic root of 129128240 is about 505.4448128046. Note that the first 3 decimals are identical.

The spelling of 129128240 in words is "one hundred twenty-nine million, one hundred twenty-eight thousand, two hundred forty".