643542641 has 8 divisors (see below), whose sum is σ = 735645504. Its totient is φ = 551481840.

The previous prime is 643542637. The next prime is 643542643. The reversal of 643542641 is 146245346.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 643542641 - 2² = 643542637 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643542643) 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 7 ways as a sum of consecutive naturals, for example, 36011 + ... + 50831.

It is an arithmetic number, because the mean of its divisors is an integer number (91955688).

Almost surely, 2^643542641 is an apocalyptic number.

It is an amenable number.

643542641 is a deficient number, since it is larger than the sum of its proper divisors (92102863).

643542641 is a wasteful number, since it uses less digits than its factorization.

643542641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21031.

The product of its digits is 69120, while the sum is 35.

The square root of 643542641 is about 25368.1422457381. The cubic root of 643542641 is about 863.3610320748.

Adding to 643542641 its reverse (146245346), we get a palindrome (789787987).

The spelling of 643542641 in words is "six hundred forty-three million, five hundred forty-two thousand, six hundred forty-one".