643542736 has 20 divisors (see below), whose sum is σ = 1267999200. Its totient is φ = 316317152.

The previous prime is 643542721. The next prime is 643542791. The reversal of 643542736 is 637245346.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 339916 + ... + 341803.

It is an arithmetic number, because the mean of its divisors is an integer number (63399960).

Almost surely, 2^643542736 is an apocalyptic number.

It is an amenable number.

643542736 is a deficient number, since it is larger than the sum of its proper divisors (624456464).

643542736 is a wasteful number, since it uses less digits than its factorization.

643542736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 681786 (or 681780 counting only the distinct ones).

The product of its digits is 362880, while the sum is 40.

The square root of 643542736 is about 25368.1441181652. The cubic root of 643542736 is about 863.3610745580.

The spelling of 643542736 in words is "six hundred forty-three million, five hundred forty-two thousand, seven hundred thirty-six".