645213893 has 2 divisors, whose sum is σ = 645213894. Its totient is φ = 645213892.

The previous prime is 645213887. The next prime is 645213929. The reversal of 645213893 is 398312546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 629357569 + 15856324 = 25087^2 + 3982^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645213893 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 645213893.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645213883) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322606946 + 322606947.

It is an arithmetic number, because the mean of its divisors is an integer number (322606947).

Almost surely, 2^645213893 is an apocalyptic number.

It is an amenable number.

645213893 is a deficient number, since it is larger than the sum of its proper divisors (1).

645213893 is an equidigital number, since it uses as much as digits as its factorization.

645213893 is an evil number, because the sum of its binary digits is even.

The product of its digits is 155520, while the sum is 41.

The square root of 645213893 is about 25401.0608636726. The cubic root of 645213893 is about 864.1077562827.

The spelling of 645213893 in words is "six hundred forty-five million, two hundred thirteen thousand, eight hundred ninety-three".