1720320 has 120 divisors (see below), whose sum is σ = 6291264. Its totient is φ = 393216.

The previous prime is 1720307. The next prime is 1720321. The reversal of 1720320 is 230271.

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a nialpdrome in base 8.

It is a self number, because there is not a number n which added to its sum of digits gives 1720320.

It is not an unprimeable number, because it can be changed into a prime (1720321) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 245757 + ... + 245763.

2^1720320 is an apocalyptic number.

1720320 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 1720320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3145632).

1720320 is an abundant number, since it is smaller than the sum of its proper divisors (4570944).

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

1720320 is an frugal number, since it uses more digits than its factorization.

1720320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43 (or 17 counting only the distinct ones).

The product of its (nonzero) digits is 84, while the sum is 15.

The square root of 1720320 is about 1311.6096980428. The cubic root of 1720320 is about 119.8219581955.

Adding to 1720320 its reverse (230271), we get a palindrome (1950591).

The spelling of 1720320 in words is "one million, seven hundred twenty thousand, three hundred twenty".