171138588721 has 3 divisors (see below), whose sum is σ = 171139002411. Its totient is φ = 171138175032.

The previous prime is 171138588703. The next prime is 171138588769. The reversal of 171138588721 is 127885831171.

The square root of 171138588721 is 413689.

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., 23866851121 + 147271737600 = 154489^2 + 383760^2 .

It is not a de Polignac number, because 171138588721 - 2¹⁵ = 171138555953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (171138580721) 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, 206845 + ... + 620533.

It is an arithmetic number, because the mean of its divisors is an integer number (57046334137).

Almost surely, 2^171138588721 is an apocalyptic number.

171138588721 is the 413689-th square number.

171138588721 is the 206845-th centered octagonal number.

It is an amenable number.

171138588721 is a deficient number, since it is larger than the sum of its proper divisors (413690).

171138588721 is an frugal number, since it uses more digits than its factorization.

171138588721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 827378 (or 413689 counting only the distinct ones).

The product of its digits is 752640, while the sum is 52.

The spelling of 171138588721 in words is "one hundred seventy-one billion, one hundred thirty-eight million, five hundred eighty-eight thousand, seven hundred twenty-one".