721220 has 12 divisors (see below), whose sum is σ = 1514604. Its totient is φ = 288480.

The previous prime is 721219. The next prime is 721223. The reversal of 721220 is 22127.

It can be written as a sum of positive squares in 2 ways, for example, as 222784 + 498436 = 472^2 + 706^2 .

It is a junction number, because it is equal to n+sod(n) for n = 721195 and 721204.

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 3 ways as a sum of consecutive naturals, for example, 18011 + ... + 18050.

It is an arithmetic number, because the mean of its divisors is an integer number (126217).

2⁷²¹²²⁰ is an apocalyptic number.

It is an amenable number.

721220 is an abundant number, since it is smaller than the sum of its proper divisors (793384).

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

721220 is a wasteful number, since it uses less digits than its factorization.

721220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36070 (or 36068 counting only the distinct ones).

The product of its (nonzero) digits is 56, while the sum is 14.

The square root of 721220 is about 849.2467250452. The cubic root of 721220 is about 89.6786896411.

Adding to 721220 its reverse (22127), we get a palindrome (743347).

The spelling of 721220 in words is "seven hundred twenty-one thousand, two hundred twenty", and thus it is an iban number.