643501687 has 2 divisors, whose sum is σ = 643501688. Its totient is φ = 643501686.

The previous prime is 643501657. The next prime is 643501693. The reversal of 643501687 is 786105346.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 643501687 - 2¹¹ = 643499639 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643501637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321750843 + 321750844.

It is an arithmetic number, because the mean of its divisors is an integer number (321750844).

Almost surely, 2^643501687 is an apocalyptic number.

643501687 is a deficient number, since it is larger than the sum of its proper divisors (1).

643501687 is an equidigital number, since it uses as much as digits as its factorization.

643501687 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 120960, while the sum is 40.

The square root of 643501687 is about 25367.3350393769. The cubic root of 643501687 is about 863.3427173921.

The spelling of 643501687 in words is "six hundred forty-three million, five hundred one thousand, six hundred eighty-seven".