171720220 has 48 divisors (see below), whose sum is σ = 414908928. Its totient is φ = 58478400.

The previous prime is 171720203. The next prime is 171720239. The reversal of 171720220 is 22027171.

171720220 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 171720191 and 171720200.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17079 + ... + 25201.

It is an arithmetic number, because the mean of its divisors is an integer number (8643936).

Almost surely, 2^171720220 is an apocalyptic number.

171720220 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 171720220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (207454464).

171720220 is an abundant number, since it is smaller than the sum of its proper divisors (243188708).

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

171720220 is a wasteful number, since it uses less digits than its factorization.

171720220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8290 (or 8288 counting only the distinct ones).

The product of its (nonzero) digits is 392, while the sum is 22.

The square root of 171720220 is about 13104.2061949589. The cubic root of 171720220 is about 555.8280742689.

Adding to 171720220 its reverse (22027171), we get a palindrome (193747391).

The spelling of 171720220 in words is "one hundred seventy-one million, seven hundred twenty thousand, two hundred twenty".