645646513 has 2 divisors, whose sum is σ = 645646514. Its totient is φ = 645646512.

The previous prime is 645646511. The next prime is 645646571. The reversal of 645646513 is 315646546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 610682944 + 34963569 = 24712^2 + 5913^2 .

It is a cyclic number.

It is not a de Polignac number, because 645646513 - 2¹ = 645646511 is a prime.

Together with 645646511, it forms a pair of twin primes.

It is equal to p_33578743 and since 645646513 and 33578743 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (645646511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322823256 + 322823257.

It is an arithmetic number, because the mean of its divisors is an integer number (322823257).

Almost surely, 2^645646513 is an apocalyptic number.

It is an amenable number.

645646513 is a deficient number, since it is larger than the sum of its proper divisors (1).

645646513 is an equidigital number, since it uses as much as digits as its factorization.

645646513 is an evil number, because the sum of its binary digits is even.

The product of its digits is 259200, while the sum is 40.

The square root of 645646513 is about 25409.5752227384. The cubic root of 645646513 is about 864.3008430408.

The spelling of 645646513 in words is "six hundred forty-five million, six hundred forty-six thousand, five hundred thirteen".