645813013 has 2 divisors, whose sum is σ = 645813014. Its totient is φ = 645813012.

The previous prime is 645813011. The next prime is 645813019. The reversal of 645813013 is 310318546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 641963569 + 3849444 = 25337^2 + 1962^2 .

It is a cyclic number.

It is not a de Polignac number, because 645813013 - 2¹ = 645813011 is a prime.

Together with 645813011, 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 (645813011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322906506 + 322906507.

It is an arithmetic number, because the mean of its divisors is an integer number (322906507).

Almost surely, 2^645813013 is an apocalyptic number.

It is an amenable number.

645813013 is a deficient number, since it is larger than the sum of its proper divisors (1).

645813013 is an equidigital number, since it uses as much as digits as its factorization.

645813013 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 645813013 is about 25412.8513354956. The cubic root of 645813013 is about 864.3751322579.

The spelling of 645813013 in words is "six hundred forty-five million, eight hundred thirteen thousand, thirteen".