129521720 has 64 divisors (see below), whose sum is σ = 305510400. Its totient is φ = 49357440.

The previous prime is 129521669. The next prime is 129521723. The reversal of 129521720 is 27125921.

It is a super-3 number, since 3×129521720³ (a number of 25 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129521723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 82301 + ... + 83859.

It is an arithmetic number, because the mean of its divisors is an integer number (4773600).

Almost surely, 2^129521720 is an apocalyptic number.

129521720 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 129521720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (152755200).

129521720 is an abundant number, since it is smaller than the sum of its proper divisors (175988680).

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

129521720 is a wasteful number, since it uses less digits than its factorization.

129521720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1668 (or 1664 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 29.

The square root of 129521720 is about 11380.7609587409. The cubic root of 129521720 is about 505.9576899116.

The spelling of 129521720 in words is "one hundred twenty-nine million, five hundred twenty-one thousand, seven hundred twenty".