129109840 has 20 divisors (see below), whose sum is σ = 300180564. Its totient is φ = 51643904.

The previous prime is 129109837. The next prime is 129109901. The reversal of 129109840 is 48901921.

It can be written as a sum of positive squares in 2 ways, for example, as 20866624 + 108243216 = 4568^2 + 10404^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a junction number, because it is equal to n+sod(n) for n = 129109796 and 129109805.

It is a congruent number.

It is an unprimeable number.

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, 806857 + ... + 807016.

Almost surely, 2^129109840 is an apocalyptic number.

129109840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

129109840 is an abundant number, since it is smaller than the sum of its proper divisors (171070724).

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

129109840 is a wasteful number, since it uses less digits than its factorization.

129109840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1613886 (or 1613880 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 34.

The square root of 129109840 is about 11362.6510991053. The cubic root of 129109840 is about 505.4208040457.

The spelling of 129109840 in words is "one hundred twenty-nine million, one hundred nine thousand, eight hundred forty".