129820 has 12 divisors (see below), whose sum is σ = 272664. Its totient is φ = 51920.

The previous prime is 129803. The next prime is 129841. The reversal of 129820 is 28921.

It is a junction number, because it is equal to n+sod(n) for n = 129791 and 129800.

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 3 ways as a sum of consecutive naturals, for example, 3226 + ... + 3265.

It is an arithmetic number, because the mean of its divisors is an integer number (22722).

2¹²⁹⁸²⁰ is an apocalyptic number.

129820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

129820 is an abundant number, since it is smaller than the sum of its proper divisors (142844).

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

129820 is a wasteful number, since it uses less digits than its factorization.

129820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6500 (or 6498 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 129820 is about 360.3054259930. The cubic root of 129820 is about 50.6345787900.

It can be divided in two parts, 129 and 820, that added together give a palindrome (949).

The spelling of 129820 in words is "one hundred twenty-nine thousand, eight hundred twenty".