643444347 has 24 divisors (see below), whose sum is σ = 1061716224. Its totient is φ = 339397344.

The previous prime is 643444267. The next prime is 643444363. The reversal of 643444347 is 743444346.

It is not a de Polignac number, because 643444347 - 2¹² = 643440251 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (643444397) 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 23 ways as a sum of consecutive naturals, for example, 87103 + ... + 94200.

It is an arithmetic number, because the mean of its divisors is an integer number (44238176).

Almost surely, 2^643444347 is an apocalyptic number.

643444347 is a deficient number, since it is larger than the sum of its proper divisors (418271877).

643444347 is a wasteful number, since it uses less digits than its factorization.

643444347 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 181339 (or 181326 counting only the distinct ones).

The product of its digits is 387072, while the sum is 39.

The square root of 643444347 is about 25366.2048205876. The cubic root of 643444347 is about 863.3170735630.

Subtracting 643444347 from its reverse (743444346), we obtain a palindrome (99999999).

The spelling of 643444347 in words is "six hundred forty-three million, four hundred forty-four thousand, three hundred forty-seven".