129115728 has 80 divisors (see below), whose sum is σ = 423564160. Its totient is φ = 36889344.

The previous prime is 129115717. The next prime is 129115729. The reversal of 129115728 is 827511921.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 129115692 and 129115701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129115729) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18325 + ... + 24372.

It is an arithmetic number, because the mean of its divisors is an integer number (5294552).

Almost surely, 2^129115728 is an apocalyptic number.

129115728 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

129115728 is an abundant number, since it is smaller than the sum of its proper divisors (294448432).

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

129115728 is a wasteful number, since it uses less digits than its factorization.

129115728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42721 (or 42709 counting only the distinct ones).

The product of its digits is 10080, while the sum is 36.

The square root of 129115728 is about 11362.9101906158. The cubic root of 129115728 is about 505.4284870967.

The spelling of 129115728 in words is "one hundred twenty-nine million, one hundred fifteen thousand, seven hundred twenty-eight".