129091175721 has 12 divisors (see below), whose sum is σ = 186468409972. Its totient is φ = 86059224576.

The previous prime is 129091175687. The next prime is 129091175729. The reversal of 129091175721 is 127571190921.

It can be written as a sum of positive squares in 2 ways, for example, as 74018820096 + 55072355625 = 272064^2 + 234675^2 .

It is not a de Polignac number, because 129091175721 - 2¹⁵ = 129091142953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (129091175729) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 625665 + ... + 806001.

Almost surely, 2^129091175721 is an apocalyptic number.

It is an amenable number.

129091175721 is a deficient number, since it is larger than the sum of its proper divisors (57377234251).

129091175721 is a wasteful number, since it uses less digits than its factorization.

129091175721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 259880 (or 259877 counting only the distinct ones).

The product of its (nonzero) digits is 79380, while the sum is 45.

The spelling of 129091175721 in words is "one hundred twenty-nine billion, ninety-one million, one hundred seventy-five thousand, seven hundred twenty-one".