720845 has 4 divisors (see below), whose sum is σ = 865020. Its totient is φ = 576672.

The previous prime is 720829. The next prime is 720847. The reversal of 720845 is 548027.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 548027 = 239 ⋅2293.

It can be written as a sum of positive squares in 2 ways, for example, as 174724 + 546121 = 418^2 + 739^2 .

It is a cyclic number.

It is not a de Polignac number, because 720845 - 2⁴ = 720829 is a prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 720845.

It is not an unprimeable number, because it can be changed into a prime (720847) 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, 72080 + ... + 72089.

It is an arithmetic number, because the mean of its divisors is an integer number (216255).

2⁷²⁰⁸⁴⁵ is an apocalyptic number.

It is an amenable number.

720845 is a deficient number, since it is larger than the sum of its proper divisors (144175).

720845 is a wasteful number, since it uses less digits than its factorization.

720845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 144174.

The product of its (nonzero) digits is 2240, while the sum is 26.

The square root of 720845 is about 849.0259124432. The cubic root of 720845 is about 89.6631440661.

It can be divided in two parts, 720 and 845, that multiplied together give a square (608400 = 780²).

The spelling of 720845 in words is "seven hundred twenty thousand, eight hundred forty-five".