645304135006691 has 2 divisors, whose sum is σ = 645304135006692. Its totient is φ = 645304135006690.

The previous prime is 645304135006561. The next prime is 645304135006697. The reversal of 645304135006691 is 196600531403546.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 645304135006691 - 2³⁰ = 645303061264867 is a prime.

It is a super-2 number, since 2×645304135006691² (a number of 30 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (645304135006697) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322652067503345 + 322652067503346.

It is an arithmetic number, because the mean of its divisors is an integer number (322652067503346).

Almost surely, 2^{645304135006691} is an apocalyptic number.

645304135006691 is a deficient number, since it is larger than the sum of its proper divisors (1).

645304135006691 is an equidigital number, since it uses as much as digits as its factorization.

645304135006691 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6998400, while the sum is 53.

The spelling of 645304135006691 in words is "six hundred forty-five trillion, three hundred four billion, one hundred thirty-five million, six thousand, six hundred ninety-one".