721130609 has 2 divisors, whose sum is σ = 721130610. Its totient is φ = 721130608.

The previous prime is 721130603. The next prime is 721130611. The reversal of 721130609 is 906031127.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 494929009 + 226201600 = 22247^2 + 15040^2 .

It is a cyclic number.

It is not a de Polignac number, because 721130609 - 2²⁸ = 452695153 is a prime.

Together with 721130611, 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 (721130603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360565304 + 360565305.

It is an arithmetic number, because the mean of its divisors is an integer number (360565305).

Almost surely, 2^721130609 is an apocalyptic number.

It is an amenable number.

721130609 is a deficient number, since it is larger than the sum of its proper divisors (1).

721130609 is an equidigital number, since it uses as much as digits as its factorization.

721130609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2268, while the sum is 29.

The square root of 721130609 is about 26853.8751207344. The cubic root of 721130609 is about 896.7498443835.

The spelling of 721130609 in words is "seven hundred twenty-one million, one hundred thirty thousand, six hundred nine".