720731 has 4 divisors (see below), whose sum is σ = 786264. Its totient is φ = 655200.

The previous prime is 720703. The next prime is 720743. The reversal of 720731 is 137027.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 137027 = 11 ⋅12457.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-720731 is a prime.

It is a super-2 number, since 2×720731² = 1038906348722, which contains 22 as substring.

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 polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 32750 + ... + 32771.

It is an arithmetic number, because the mean of its divisors is an integer number (196566).

2⁷²⁰⁷³¹ is an apocalyptic number.

720731 is a deficient number, since it is larger than the sum of its proper divisors (65533).

720731 is a wasteful number, since it uses less digits than its factorization.

720731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65532.

The product of its (nonzero) digits is 294, while the sum is 20.

The square root of 720731 is about 848.9587740285. The cubic root of 720731 is about 89.6584171427.

Adding to 720731 its reverse (137027), we get a palindrome (857758).

The spelling of 720731 in words is "seven hundred twenty thousand, seven hundred thirty-one".