643786641 has 12 divisors (see below), whose sum is σ = 959911680. Its totient is φ = 415346040.

The previous prime is 643786639. The next prime is 643786657. The reversal of 643786641 is 146687346.

It is a happy number.

It is not a de Polignac number, because 643786641 - 2¹ = 643786639 is a prime.

It is a super-3 number, since 3×643786641³ (a number of 27 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (643786621) 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 in 11 ways as a sum of consecutive naturals, for example, 1153461 + ... + 1154018.

It is an arithmetic number, because the mean of its divisors is an integer number (79992640).

Almost surely, 2^643786641 is an apocalyptic number.

It is an amenable number.

643786641 is a deficient number, since it is larger than the sum of its proper divisors (316125039).

643786641 is a wasteful number, since it uses less digits than its factorization.

643786641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2307516 (or 2307513 counting only the distinct ones).

The product of its digits is 580608, while the sum is 45.

The square root of 643786641 is about 25372.9509714578. The cubic root of 643786641 is about 863.4701330936.

The spelling of 643786641 in words is "six hundred forty-three million, seven hundred eighty-six thousand, six hundred forty-one".