645918193 has 2 divisors, whose sum is σ = 645918194. Its totient is φ = 645918192.

The previous prime is 645918181. The next prime is 645918211. The reversal of 645918193 is 391819546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 591851584 + 54066609 = 24328^2 + 7353^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645918193 is a prime.

It is not a weakly prime, because it can be changed into another prime (645918103) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322959096 + 322959097.

It is an arithmetic number, because the mean of its divisors is an integer number (322959097).

Almost surely, 2^645918193 is an apocalyptic number.

It is an amenable number.

645918193 is a deficient number, since it is larger than the sum of its proper divisors (1).

645918193 is an equidigital number, since it uses as much as digits as its factorization.

645918193 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 233280, while the sum is 46.

The square root of 645918193 is about 25414.9206766419. The cubic root of 645918193 is about 864.4220550459.

The spelling of 645918193 in words is "six hundred forty-five million, nine hundred eighteen thousand, one hundred ninety-three".