643864536 has 192 divisors, whose sum is σ = 2050713600. Its totient is φ = 178723584.

The previous prime is 643864531. The next prime is 643864547. The reversal of 643864536 is 635468346.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 643864491 and 643864500.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643864531) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 4100970 + ... + 4101126.

It is an arithmetic number, because the mean of its divisors is an integer number (10680800).

Almost surely, 2^643864536 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643864536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1025356800).

643864536 is an abundant number, since it is smaller than the sum of its proper divisors (1406849064).

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

643864536 is a wasteful number, since it uses less digits than its factorization.

643864536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 358 (or 351 counting only the distinct ones).

The product of its digits is 1244160, while the sum is 45.

The square root of 643864536 is about 25374.4859258271. The cubic root of 643864536 is about 863.5049568946.

The spelling of 643864536 in words is "six hundred forty-three million, eight hundred sixty-four thousand, five hundred thirty-six".