171720 has 80 divisors (see below), whose sum is σ = 588060. Its totient is φ = 44928.

The previous prime is 171719. The next prime is 171733. The reversal of 171720 is 27171.

171720 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 171396 + 324 = 414^2 + 18^2 .

It is a hoax number, since the sum of its digits (18) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 171693 and 171702.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 3214 + ... + 3266.

2¹⁷¹⁷²⁰ is an apocalyptic number.

171720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 171720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (294030).

171720 is an abundant number, since it is smaller than the sum of its proper divisors (416340).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

171720 is a wasteful number, since it uses less digits than its factorization.

171720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76 (or 63 counting only the distinct ones).

The product of its (nonzero) digits is 98, while the sum is 18.

The square root of 171720 is about 414.3911195960. The cubic root of 171720 is about 55.5827836902.

Adding to 171720 its reverse (27171), we get a palindrome (198891).

The spelling of 171720 in words is "one hundred seventy-one thousand, seven hundred twenty", and thus it is an iban number.