643523687 has 2 divisors, whose sum is σ = 643523688. Its totient is φ = 643523686.

The previous prime is 643523641. The next prime is 643523707. The reversal of 643523687 is 786325346.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643523687 is a prime.

It is a congruent number.

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, 321761843 + 321761844.

It is an arithmetic number, because the mean of its divisors is an integer number (321761844).

Almost surely, 2^643523687 is an apocalyptic number.

643523687 is a deficient number, since it is larger than the sum of its proper divisors (1).

643523687 is an equidigital number, since it uses as much as digits as its factorization.

643523687 is an evil number, because the sum of its binary digits is even.

The product of its digits is 725760, while the sum is 44.

The square root of 643523687 is about 25367.7686641928. The cubic root of 643523687 is about 863.3525559176.

The spelling of 643523687 in words is "six hundred forty-three million, five hundred twenty-three thousand, six hundred eighty-seven".