129440 has 24 divisors (see below), whose sum is σ = 306180. Its totient is φ = 51712.

The previous prime is 129439. The next prime is 129443. The reversal of 129440 is 44921.

It can be written as a sum of positive squares in 2 ways, for example, as 126736 + 2704 = 356^2 + 52^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a plaindrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129443) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 245 + ... + 564.

2¹²⁹⁴⁴⁰ is an apocalyptic number.

129440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

129440 is an abundant number, since it is smaller than the sum of its proper divisors (176740).

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

129440 is an equidigital number, since it uses as much as digits as its factorization.

129440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 824 (or 816 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 129440 is about 359.7777091483. Note that the first 4 decimals coincide. The cubic root of 129440 is about 50.5851258441.

The spelling of 129440 in words is "one hundred twenty-nine thousand, four hundred forty".