643665942 has 12 divisors (see below), whose sum is σ = 1394609580. Its totient is φ = 214555308.

The previous prime is 643665941. The next prime is 643665947. The reversal of 643665942 is 249566346.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643665941) 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 5 ways as a sum of consecutive naturals, for example, 17879592 + ... + 17879627.

It is an arithmetic number, because the mean of its divisors is an integer number (116217465).

Almost surely, 2^643665942 is an apocalyptic number.

643665942 is an abundant number, since it is smaller than the sum of its proper divisors (750943638).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

643665942 is a wasteful number, since it uses less digits than its factorization.

643665942 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35759227 (or 35759224 counting only the distinct ones).

The product of its digits is 933120, while the sum is 45.

The square root of 643665942 is about 25370.5723624833. The cubic root of 643665942 is about 863.4161677534.

The spelling of 643665942 in words is "six hundred forty-three million, six hundred sixty-five thousand, nine hundred forty-two".