161730720 has 144 divisors (see below), whose sum is σ = 569866752. Its totient is φ = 41725440.

The previous prime is 161730643. The next prime is 161730727. The reversal of 161730720 is 27037161.

It is a tau number, because it is divible by the number of its divisors (144).

It is not an unprimeable number, because it can be changed into a prime (161730727) 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 23 ways as a sum of consecutive naturals, for example, 42829 + ... + 46451.

It is an arithmetic number, because the mean of its divisors is an integer number (3957408).

Almost surely, 2^161730720 is an apocalyptic number.

161730720 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 161730720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (284933376).

161730720 is an abundant number, since it is smaller than the sum of its proper divisors (408136032).

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

161730720 is a wasteful number, since it uses less digits than its factorization.

161730720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3675 (or 3664 counting only the distinct ones).

The product of its (nonzero) digits is 1764, while the sum is 27.

The square root of 161730720 is about 12717.3393443755. The cubic root of 161730720 is about 544.8339645162.

Adding to 161730720 its reverse (27037161), we get a palindrome (188767881).

The spelling of 161730720 in words is "one hundred sixty-one million, seven hundred thirty thousand, seven hundred twenty".