643523897 has 2 divisors, whose sum is σ = 643523898. Its totient is φ = 643523896.

The previous prime is 643523887. The next prime is 643523921. The reversal of 643523897 is 798325346.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 338707216 + 304816681 = 18404^2 + 17459^2 .

It is a cyclic number.

It is not a de Polignac number, because 643523897 - 2⁸ = 643523641 is a prime.

It is not a weakly prime, because it can be changed into another prime (643523887) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321761948 + 321761949.

It is an arithmetic number, because the mean of its divisors is an integer number (321761949).

Almost surely, 2^643523897 is an apocalyptic number.

It is an amenable number.

643523897 is a deficient number, since it is larger than the sum of its proper divisors (1).

643523897 is an equidigital number, since it uses as much as digits as its factorization.

643523897 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1088640, while the sum is 47.

The square root of 643523897 is about 25367.7728033030. The cubic root of 643523897 is about 863.3526498298.

The spelling of 643523897 in words is "six hundred forty-three million, five hundred twenty-three thousand, eight hundred ninety-seven".