129399 has 4 divisors (see below), whose sum is σ = 172536. Its totient is φ = 86264.

The previous prime is 129379. The next prime is 129401. The reversal of 129399 is 993921.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 993921 = 3 ⋅331307.

It is a cyclic number.

It is not a de Polignac number, because 129399 - 2¹² = 125303 is a prime.

It is an Ulam number.

It is a D-number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129379) 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 3 ways as a sum of consecutive naturals, for example, 21564 + ... + 21569.

It is an arithmetic number, because the mean of its divisors is an integer number (43134).

2¹²⁹³⁹⁹ is an apocalyptic number.

129399 is a deficient number, since it is larger than the sum of its proper divisors (43137).

129399 is an equidigital number, since it uses as much as digits as its factorization.

129399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43136.

The product of its digits is 4374, while the sum is 33.

The square root of 129399 is about 359.7207250076. The cubic root of 129399 is about 50.5797843496.

It can be divided in two parts, 129 and 399, that added together give a triangular number (528 = T₃₂).

The spelling of 129399 in words is "one hundred twenty-nine thousand, three hundred ninety-nine".