645704257697 has 2 divisors, whose sum is σ = 645704257698. Its totient is φ = 645704257696.

The previous prime is 645704257663. The next prime is 645704257729. The reversal of 645704257697 is 796752407546.

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., 642075279616 + 3628978081 = 801296^2 + 60241^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645704257697 is a prime.

It is not a weakly prime, because it can be changed into another prime (645704257097) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322852128848 + 322852128849.

It is an arithmetic number, because the mean of its divisors is an integer number (322852128849).

Almost surely, 2^645704257697 is an apocalyptic number.

It is an amenable number.

645704257697 is a deficient number, since it is larger than the sum of its proper divisors (1).

645704257697 is an equidigital number, since it uses as much as digits as its factorization.

645704257697 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 88905600, while the sum is 62.

The spelling of 645704257697 in words is "six hundred forty-five billion, seven hundred four million, two hundred fifty-seven thousand, six hundred ninety-seven".