1520021509 has 2 divisors, whose sum is σ = 1520021510. Its totient is φ = 1520021508.

The previous prime is 1520021507. The next prime is 1520021513. The reversal of 1520021509 is 9051200251.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1354976100 + 165045409 = 36810^2 + 12847^2 .

It is a cyclic number.

It is not a de Polignac number, because 1520021509 - 2¹ = 1520021507 is a prime.

Together with 1520021507, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1520021507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 760010754 + 760010755.

It is an arithmetic number, because the mean of its divisors is an integer number (760010755).

Almost surely, 2^1520021509 is an apocalyptic number.

It is an amenable number.

1520021509 is a deficient number, since it is larger than the sum of its proper divisors (1).

1520021509 is an equidigital number, since it uses as much as digits as its factorization.

1520021509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 900, while the sum is 25.

The square root of 1520021509 is about 38987.4532253647. The cubic root of 1520021509 is about 1149.7848391418.

The spelling of 1520021509 in words is "one billion, five hundred twenty million, twenty-one thousand, five hundred nine".