643617613 has 2 divisors, whose sum is σ = 643617614. Its totient is φ = 643617612.

The previous prime is 643617599. The next prime is 643617617. The reversal of 643617613 is 316716346.

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., 473628169 + 169989444 = 21763^2 + 13038^2 .

It is a cyclic number.

It is not a de Polignac number, because 643617613 - 2⁵ = 643617581 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643617617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321808806 + 321808807.

It is an arithmetic number, because the mean of its divisors is an integer number (321808807).

Almost surely, 2^643617613 is an apocalyptic number.

It is an amenable number.

643617613 is a deficient number, since it is larger than the sum of its proper divisors (1).

643617613 is an equidigital number, since it uses as much as digits as its factorization.

643617613 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54432, while the sum is 37.

The square root of 643617613 is about 25369.6198828441. The cubic root of 643617613 is about 863.3945576387.

The spelling of 643617613 in words is "six hundred forty-three million, six hundred seventeen thousand, six hundred thirteen".