720173009 has 2 divisors, whose sum is σ = 720173010. Its totient is φ = 720173008.

The previous prime is 720172909. The next prime is 720173011. The reversal of 720173009 is 900371027.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 390931984 + 329241025 = 19772^2 + 18145^2 .

It is an emirp because it is prime and its reverse (900371027) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-720173009 is a prime.

It is a super-2 number, since 2×720173009² = 1037298325784228162, which contains 22 as substring.

Together with 720173011, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (720173099) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360086504 + 360086505.

It is an arithmetic number, because the mean of its divisors is an integer number (360086505).

Almost surely, 2^720173009 is an apocalyptic number.

It is an amenable number.

720173009 is a deficient number, since it is larger than the sum of its proper divisors (1).

720173009 is an equidigital number, since it uses as much as digits as its factorization.

720173009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2646, while the sum is 29.

The square root of 720173009 is about 26836.0393687295. The cubic root of 720173009 is about 896.3527327615.

The spelling of 720173009 in words is "seven hundred twenty million, one hundred seventy-three thousand, nine".