645239317 has 2 divisors, whose sum is σ = 645239318. Its totient is φ = 645239316.

The previous prime is 645239293. The next prime is 645239323. The reversal of 645239317 is 713932546.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 644448996 + 790321 = 25386^2 + 889^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645239317 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 645239317.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645239327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322619658 + 322619659.

It is an arithmetic number, because the mean of its divisors is an integer number (322619659).

Almost surely, 2^645239317 is an apocalyptic number.

It is an amenable number.

645239317 is a deficient number, since it is larger than the sum of its proper divisors (1).

645239317 is an equidigital number, since it uses as much as digits as its factorization.

645239317 is an evil number, because the sum of its binary digits is even.

The product of its digits is 136080, while the sum is 40.

The square root of 645239317 is about 25401.5613102817. The cubic root of 645239317 is about 864.1191058973.

The spelling of 645239317 in words is "six hundred forty-five million, two hundred thirty-nine thousand, three hundred seventeen".