72728009 has 4 divisors (see below), whose sum is σ = 72824340. Its totient is φ = 72631680.

The previous prime is 72727987. The next prime is 72728011. The reversal of 72728009 is 90082727.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 222784 + 72505225 = 472^2 + 8515^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-72728009 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 72728009.

It is not an unprimeable number, because it can be changed into a prime (72728039) 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, 47024 + ... + 48545.

It is an arithmetic number, because the mean of its divisors is an integer number (18206085).

Almost surely, 2^72728009 is an apocalyptic number.

It is an amenable number.

72728009 is a deficient number, since it is larger than the sum of its proper divisors (96331).

72728009 is an equidigital number, since it uses as much as digits as its factorization.

72728009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96330.

The product of its (nonzero) digits is 14112, while the sum is 35.

The square root of 72728009 is about 8528.0718219302. The cubic root of 72728009 is about 417.4142130742.

The spelling of 72728009 in words is "seventy-two million, seven hundred twenty-eight thousand, nine".