171321921 has 9 divisors (see below), whose sum is σ = 247521729. Its totient is φ = 114188436.

The previous prime is 171321911. The next prime is 171321923. The reversal of 171321921 is 129123171.

The square root of 171321921 is 13089.

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

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 171321921 - 2⁵ = 171321889 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (171321923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 37086 + ... + 41448.

Almost surely, 2^171321921 is an apocalyptic number.

171321921 is the 13089-th square number.

171321921 is the 6545-th centered octagonal number.

It is an amenable number.

171321921 is a deficient number, since it is larger than the sum of its proper divisors (76199808).

171321921 is an frugal number, since it uses more digits than its factorization.

171321921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8732 (or 4366 counting only the distinct ones).

The product of its digits is 756, while the sum is 27.

The cubic root of 171321921 is about 555.3980003720.

The spelling of 171321921 in words is "one hundred seventy-one million, three hundred twenty-one thousand, nine hundred twenty-one".