643843741 has 4 divisors (see below), whose sum is σ = 657542592. Its totient is φ = 630144892.

The previous prime is 643843729. The next prime is 643843763. The reversal of 643843741 is 147348346.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 147348346 = 2 ⋅73674173.

It is a cyclic number.

It is not a de Polignac number, because 643843741 - 2⁹ = 643843229 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 643843694 and 643843703.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643843141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6849355 + ... + 6849448.

It is an arithmetic number, because the mean of its divisors is an integer number (164385648).

Almost surely, 2^643843741 is an apocalyptic number.

It is an amenable number.

643843741 is a deficient number, since it is larger than the sum of its proper divisors (13698851).

643843741 is a wasteful number, since it uses less digits than its factorization.

643843741 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13698850.

The product of its digits is 193536, while the sum is 40.

The square root of 643843741 is about 25374.0761605226. The cubic root of 643843741 is about 863.4956605401.

The spelling of 643843741 in words is "six hundred forty-three million, eight hundred forty-three thousand, seven hundred forty-one".