726509 has 4 divisors (see below), whose sum is σ = 830304. Its totient is φ = 622716.

The previous prime is 726497. The next prime is 726521. The reversal of 726509 is 905627.

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: 905627 = 887 ⋅1021.

It is an interprime number because it is at equal distance from previous prime (726497) and next prime (726521).

It is a cyclic number.

It is not a de Polignac number, because 726509 - 2¹⁶ = 660973 is a prime.

It is a Duffinian number.

It is a Curzon number.

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 726509.

It is not an unprimeable number, because it can be changed into a prime (726559) 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, 51887 + ... + 51900.

It is an arithmetic number, because the mean of its divisors is an integer number (207576).

2⁷²⁶⁵⁰⁹ is an apocalyptic number.

It is an amenable number.

726509 is a deficient number, since it is larger than the sum of its proper divisors (103795).

726509 is a wasteful number, since it uses less digits than its factorization.

726509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103794.

The product of its (nonzero) digits is 3780, while the sum is 29.

The square root of 726509 is about 852.3549730013. The cubic root of 726509 is about 89.8973727302.

The spelling of 726509 in words is "seven hundred twenty-six thousand, five hundred nine".