128520729 has 8 divisors (see below), whose sum is σ = 190401120. Its totient is φ = 85680468.

The previous prime is 128520713. The next prime is 128520737. The reversal of 128520729 is 927025821.

128520729 is a `hidden beast` number, since 128 + 520 + 7 + 2 + 9 = 666.

It is not a de Polignac number, because 128520729 - 2⁴ = 128520713 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 128520693 and 128520702.

It is not an unprimeable number, because it can be changed into a prime (128520529) 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, 2379987 + ... + 2380040.

It is an arithmetic number, because the mean of its divisors is an integer number (23800140).

Almost surely, 2^128520729 is an apocalyptic number.

It is an amenable number.

128520729 is a deficient number, since it is larger than the sum of its proper divisors (61880391).

128520729 is an equidigital number, since it uses as much as digits as its factorization.

128520729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4760036 (or 4760030 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The square root of 128520729 is about 11336.6983288787. The cubic root of 128520729 is about 504.6509092809.

The spelling of 128520729 in words is "one hundred twenty-eight million, five hundred twenty thousand, seven hundred twenty-nine".