721320 has 32 divisors (see below), whose sum is σ = 2164320. Its totient is φ = 192320.

The previous prime is 721319. The next prime is 721321. The reversal of 721320 is 23127.

It is an interprime number because it is at equal distance from previous prime (721319) and next prime (721321).

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

It is a self number, because there is not a number n which added to its sum of digits gives 721320.

It is not an unprimeable number, because it can be changed into a prime (721321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2886 + ... + 3125.

It is an arithmetic number, because the mean of its divisors is an integer number (67635).

2⁷²¹³²⁰ is an apocalyptic number.

It is an amenable number.

721320 is an abundant number, since it is smaller than the sum of its proper divisors (1443000).

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

721320 is a wasteful number, since it uses less digits than its factorization.

721320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6025 (or 6021 counting only the distinct ones).

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

The square root of 721320 is about 849.3055987099. The cubic root of 721320 is about 89.6828342177.

Adding to 721320 its reverse (23127), we get a palindrome (744447).

The spelling of 721320 in words is "seven hundred twenty-one thousand, three hundred twenty", and thus it is an iban number.