521305009 has 2 divisors, whose sum is σ = 521305010. Its totient is φ = 521305008.

The previous prime is 521305007. The next prime is 521305049. The reversal of 521305009 is 900503125.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 452497984 + 68807025 = 21272^2 + 8295^2 .

It is a cyclic number.

It is not a de Polignac number, because 521305009 - 2¹ = 521305007 is a prime.

Together with 521305007, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (521305003) 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, 260652504 + 260652505.

It is an arithmetic number, because the mean of its divisors is an integer number (260652505).

Almost surely, 2^521305009 is an apocalyptic number.

It is an amenable number.

521305009 is a deficient number, since it is larger than the sum of its proper divisors (1).

521305009 is an equidigital number, since it uses as much as digits as its factorization.

521305009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1350, while the sum is 25.

The square root of 521305009 is about 22832.1047869004. The cubic root of 521305009 is about 804.8172927427.

The spelling of 521305009 in words is "five hundred twenty-one million, three hundred five thousand, nine".