721224 has 96 divisors (see below), whose sum is σ = 2358720. Its totient is φ = 202176.

The previous prime is 721223. The next prime is 721229. The reversal of 721224 is 422127.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 721197 and 721206.

It is not an unprimeable number, because it can be changed into a prime (721223) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13582 + ... + 13634.

It is an arithmetic number, because the mean of its divisors is an integer number (24570).

2⁷²¹²²⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 721224, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1179360).

721224 is an abundant number, since it is smaller than the sum of its proper divisors (1637496).

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

721224 is a wasteful number, since it uses less digits than its factorization.

721224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81 (or 65 counting only the distinct ones).

The product of its digits is 224, while the sum is 18.

The square root of 721224 is about 849.2490800702. The cubic root of 721224 is about 89.6788554315.

It can be divided in two parts, 72 and 1224, that added together give a 4-th power (1296 = 6⁴).

The spelling of 721224 in words is "seven hundred twenty-one thousand, two hundred twenty-four", and thus it is an iban number.