645123317 has 2 divisors, whose sum is σ = 645123318. Its totient is φ = 645123316.

The previous prime is 645123313. The next prime is 645123337. The reversal of 645123317 is 713321546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 478996996 + 166126321 = 21886^2 + 12889^2 .

It is a cyclic number.

It is not a de Polignac number, because 645123317 - 2² = 645123313 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645123313) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322561658 + 322561659.

It is an arithmetic number, because the mean of its divisors is an integer number (322561659).

Almost surely, 2^645123317 is an apocalyptic number.

It is an amenable number.

645123317 is a deficient number, since it is larger than the sum of its proper divisors (1).

645123317 is an equidigital number, since it uses as much as digits as its factorization.

645123317 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15120, while the sum is 32.

The square root of 645123317 is about 25399.2778834360. The cubic root of 645123317 is about 864.0673195181.

The spelling of 645123317 in words is "six hundred forty-five million, one hundred twenty-three thousand, three hundred seventeen".