128729664 has 126 divisors (see below), whose sum is σ = 429316134. Its totient is φ = 36771840.

The previous prime is 128729641. The next prime is 128729669. The reversal of 128729664 is 466927821.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 101606400 + 27123264 = 10080^2 + 5208^2 .

It is a tau number, because it is divible by the number of its divisors (126).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (128729669) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 25944 + ... + 30504.

Almost surely, 2^128729664 is an apocalyptic number.

128729664 is a gapful number since it is divisible by the number (14) 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 128729664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (214658067).

128729664 is an abundant number, since it is smaller than the sum of its proper divisors (300586470).

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

128729664 is a wasteful number, since it uses less digits than its factorization.

128729664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4593 (or 4573 counting only the distinct ones).

The product of its digits is 290304, while the sum is 45.

The square root of 128729664 is about 11345.9095712948. The cubic root of 128729664 is about 504.9242300463.

The spelling of 128729664 in words is "one hundred twenty-eight million, seven hundred twenty-nine thousand, six hundred sixty-four".