1791509971729 has 3 divisors (see below), whose sum is σ = 1791511310203. Its totient is φ = 1791508633256.

The previous prime is 1791509971681. The next prime is 1791509971763. The reversal of 1791509971729 is 9271799051971.

The square root of 1791509971729 is 1338473.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 9947070225 + 1781562901504 = 99735^2 + 1334752^2 .

It is not a de Polignac number, because 1791509971729 - 2²⁹ = 1790973100817 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1791509971829) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 669237 + ... + 2007709.

Almost surely, 2^{1791509971729} is an apocalyptic number.

1791509971729 is the 1338473-rd square number.

1791509971729 is the 669237-th centered octagonal number.

It is an amenable number.

1791509971729 is a deficient number, since it is larger than the sum of its proper divisors (1338474).

1791509971729 is an frugal number, since it uses more digits than its factorization.

1791509971729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2676946 (or 1338473 counting only the distinct ones).

The product of its (nonzero) digits is 22504230, while the sum is 67.

The spelling of 1791509971729 in words is "one trillion, seven hundred ninety-one billion, five hundred nine million, nine hundred seventy-one thousand, seven hundred twenty-nine".