129705556217 has 6 divisors (see below), whose sum is σ = 137784103278. Its totient is φ = 122075817344.

The previous prime is 129705556213. The next prime is 129705556229. The reversal of 129705556217 is 712655507921.

It can be written as a sum of positive squares in 3 ways, for example, as 41035010041 + 88670546176 = 202571^2 + 297776^2 .

It is not a de Polignac number, because 129705556217 - 2² = 129705556213 is a prime.

It is a super-2 number, since 2×129705556217² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (129705556213) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 224403788 + ... + 224404365.

It is an arithmetic number, because the mean of its divisors is an integer number (22964017213).

Almost surely, 2^129705556217 is an apocalyptic number.

129705556217 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

It is an amenable number.

129705556217 is a deficient number, since it is larger than the sum of its proper divisors (8078547061).

129705556217 is an equidigital number, since it uses as much as digits as its factorization.

129705556217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 448808187 (or 448808170 counting only the distinct ones).

The product of its (nonzero) digits is 1323000, while the sum is 50.

The spelling of 129705556217 in words is "one hundred twenty-nine billion, seven hundred five million, five hundred fifty-six thousand, two hundred seventeen".