129720 has 64 divisors (see below), whose sum is σ = 414720. Its totient is φ = 32384.

The previous prime is 129719. The next prime is 129733. The reversal of 129720 is 27921.

Added to its reverse (27921) it gives a triangular number (157641 = T₅₆₁).

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2737 + ... + 2783.

It is an arithmetic number, because the mean of its divisors is an integer number (6480).

2¹²⁹⁷²⁰ is an apocalyptic number.

129720 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 129720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (207360).

129720 is an abundant number, since it is smaller than the sum of its proper divisors (285000).

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

129720 is a wasteful number, since it uses less digits than its factorization.

129720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84 (or 80 counting only the distinct ones).

The product of its (nonzero) digits is 252, while the sum is 21.

The square root of 129720 is about 360.1666281043. The cubic root of 129720 is about 50.6215742233.

Adding to 129720 its reverse (27921), we get a triangular number (157641 = T₅₆₁).

The spelling of 129720 in words is "one hundred twenty-nine thousand, seven hundred twenty".