129172217505 has 16 divisors (see below), whose sum is σ = 207533128704. Its totient is φ = 68605989120.

The previous prime is 129172217453. The next prime is 129172217509. The reversal of 129172217505 is 505712271921.

It is not a de Polignac number, because 129172217505 - 2¹¹ = 129172215457 is a prime.

It is not an unprimeable number, because it can be changed into a prime (129172217509) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17862529 + ... + 17869758.

It is an arithmetic number, because the mean of its divisors is an integer number (12970820544).

Almost surely, 2^129172217505 is an apocalyptic number.

129172217505 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

129172217505 is a deficient number, since it is larger than the sum of its proper divisors (78360911199).

129172217505 is a wasteful number, since it uses less digits than its factorization.

129172217505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35732536.

The product of its (nonzero) digits is 88200, while the sum is 42.

The spelling of 129172217505 in words is "one hundred twenty-nine billion, one hundred seventy-two million, two hundred seventeen thousand, five hundred five".