646135691 has 2 divisors, whose sum is σ = 646135692. Its totient is φ = 646135690.

The previous prime is 646135681. The next prime is 646135709. The reversal of 646135691 is 196531646.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-646135691 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (646135601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323067845 + 323067846.

It is an arithmetic number, because the mean of its divisors is an integer number (323067846).

Almost surely, 2^646135691 is an apocalyptic number.

646135691 is a deficient number, since it is larger than the sum of its proper divisors (1).

646135691 is an equidigital number, since it uses as much as digits as its factorization.

646135691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 116640, while the sum is 41.

The square root of 646135691 is about 25419.1992596148. The cubic root of 646135691 is about 864.5190688636.

The spelling of 646135691 in words is "six hundred forty-six million, one hundred thirty-five thousand, six hundred ninety-one".