170721216 has 112 divisors (see below), whose sum is σ = 518241280. Its totient is φ = 55054080.

The previous prime is 170721193. The next prime is 170721217. The reversal of 170721216 is 612127071.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 170721216.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (170721217) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 51975 + ... + 55161.

Almost surely, 2^170721216 is an apocalyptic number.

170721216 is a gapful number since it is divisible by the number (16) 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 170721216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (259120640).

170721216 is an abundant number, since it is smaller than the sum of its proper divisors (347520064).

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

170721216 is a wasteful number, since it uses less digits than its factorization.

170721216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3239 (or 3223 counting only the distinct ones).

The product of its (nonzero) digits is 1176, while the sum is 27.

The square root of 170721216 is about 13066.0329098009. The cubic root of 170721216 is about 554.7481106779.

Adding to 170721216 its reverse (612127071), we get a palindrome (782848287).

The spelling of 170721216 in words is "one hundred seventy million, seven hundred twenty-one thousand, two hundred sixteen".