645339509 has 2 divisors, whose sum is σ = 645339510. Its totient is φ = 645339508.

The previous prime is 645339449. The next prime is 645339517. The reversal of 645339509 is 905933546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 628504900 + 16834609 = 25070^2 + 4103^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645339509 is a prime.

It is a super-2 number, since 2×645339509² = 832926163752722162, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 645339509.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645339559) 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, 322669754 + 322669755.

It is an arithmetic number, because the mean of its divisors is an integer number (322669755).

Almost surely, 2^645339509 is an apocalyptic number.

It is an amenable number.

645339509 is a deficient number, since it is larger than the sum of its proper divisors (1).

645339509 is an equidigital number, since it uses as much as digits as its factorization.

645339509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 437400, while the sum is 44.

The square root of 645339509 is about 25403.5333959668. The cubic root of 645339509 is about 864.1638300476.

The spelling of 645339509 in words is "six hundred forty-five million, three hundred thirty-nine thousand, five hundred nine".