720721 has 4 divisors (see below), whose sum is σ = 730944. Its totient is φ = 710500.

The previous prime is 720703. The next prime is 720743. The reversal of 720721 is 127027.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 127027 = 59 ⋅2153.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-720721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (720791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5005 + ... + 5146.

It is an arithmetic number, because the mean of its divisors is an integer number (182736).

2⁷²⁰⁷²¹ is an apocalyptic number.

720721 is a gapful number since it is divisible by the number (71) formed by its first and last digit.

It is an amenable number.

720721 is a deficient number, since it is larger than the sum of its proper divisors (10223).

720721 is a wasteful number, since it uses less digits than its factorization.

720721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10222.

The product of its (nonzero) digits is 196, while the sum is 19.

The square root of 720721 is about 848.9528844406. The cubic root of 720721 is about 89.6580024765.

Adding to 720721 its reverse (127027), we get a palindrome (847748).

It can be divided in two parts, 720 and 721, that added together give a palindrome (1441).

The spelling of 720721 in words is "seven hundred twenty thousand, seven hundred twenty-one", and thus it is an iban number.