171121720 has 96 divisors (see below), whose sum is σ = 488663280. Its totient is φ = 53329920.

The previous prime is 171121693. The next prime is 171121723. The reversal of 171121720 is 27121171.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a junction number, because it is equal to n+sod(n) for n = 171121691 and 171121700.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (171121723) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17592 + ... + 25528.

Almost surely, 2^171121720 is an apocalyptic number.

171121720 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 171121720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (244331640).

171121720 is an abundant number, since it is smaller than the sum of its proper divisors (317541560).

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

171121720 is a wasteful number, since it uses less digits than its factorization.

171121720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7973 (or 7962 counting only the distinct ones).

The product of its (nonzero) digits is 196, while the sum is 22.

The square root of 171121720 is about 13081.3500832292. The cubic root of 171121720 is about 555.1815762780.

Adding to 171121720 its reverse (27121171), we get a palindrome (198242891).

The spelling of 171121720 in words is "one hundred seventy-one million, one hundred twenty-one thousand, seven hundred twenty".